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‎chapter-5-pointers-and-arrays/42.dcl.c‎

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#include <stdio.h>
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#include <string.h>
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#include <ctype.h>
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#define MAXTOKEN 100
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enum { NAME, PARENS, BRACKETS };
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void dcl(void);
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void dirdcl(void);
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int gettoken(void);
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int tokentype; // type of last token
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char token[MAXTOKEN]; // last token string
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char name[MAXTOKEN]; // identifier name
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char datatype[MAXTOKEN]; // data type = char, int, etc.
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char out[1000]; // output string
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// gcc 42.dcl.c getch.c
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main()
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{
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while (gettoken() != EOF) { // 1st token on line
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strcpy(datatype, token);
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out[0] = '\0';
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dcl();
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if (tokentype != '\n')
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printf("syntax error\n");
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printf("%s: %s %s\n", name, out, datatype);
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}
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return 0;
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}
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void dcl(void)
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{
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int ns;
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for (ns = 0; gettoken() == '*';)
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ns++;
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dirdcl();
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while (ns-- > 0)
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strcat(out, " pointer to");
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}
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void dirdcl(void)
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{
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int type;
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if (tokentype == '(') {
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dcl();
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if (tokentype != ')')
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printf("error: missing )\n");
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} else if (tokentype == NAME)
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strcpy(name, token);
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else
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printf("error: expected name or (dcl)\n");
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while ((type = gettoken()) == PARENS || type == BRACKETS)
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if (type == PARENS)
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strcat(out, " function returning");
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else {
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strcat(out, " array");
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strcat(out, token);
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strcat(out, " of");
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}
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}
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int gettoken(void)
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{
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int c, getch(void);
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void ungetch(int);
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char *p = token;
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while ((c = getch()) == ' ' || c == '\t')
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;
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if (c == '(') {
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if ((c = getch()) == ')') {
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strcpy(token, "()");
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return tokentype = PARENS;
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} else {
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ungetch(c);
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return tokentype = '(';
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}
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} else if (c == '[') {
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for (*p++ = c; (*p++ = getch()) != ']'; )
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;
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*p = '\0';
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return tokentype = BRACKETS;
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} else if (isalpha(c)) {
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for (*p++ = c; isalnum(c = getch()); )
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*p++ = c;
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*p = '\0';
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ungetch(c);
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return tokentype = NAME;
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} else {
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return tokentype = c;
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}
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}
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‎chapter-5-pointers-and-arrays/43.dcl-error-handle.c‎

Lines changed: 127 additions & 0 deletions
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#include <stdio.h>
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#include <string.h>
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#include <ctype.h>
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#define MAXTOKEN 100
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#define DATATYPE_LEN 6
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enum { NAME, PARENS, BRACKETS };
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void dcl(void);
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void dirdcl(void);
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int isvalid_datatype(const char*);
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int gettoken(void);
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int tokentype; // type of last token
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char token[MAXTOKEN]; // last token string
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char name[MAXTOKEN]; // identifier name
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char datatype[MAXTOKEN]; // data type = char, int, etc.
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char out[1000]; // output string
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// gcc 43.dcl-error-handle.c getch.c
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main()
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{
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while (gettoken() != EOF) { // 1st token on line
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strcpy(datatype, token);
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if (tokentype != NAME) {
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printf("%c is not a valid datatype\n", tokentype);
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continue;
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} else if (!isvalid_datatype(datatype)) {
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printf("%s is not a valid datatype\n", datatype);
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continue;
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}
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out[0] = '\0';
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dcl();
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if (tokentype != '\n')
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printf("syntax error\n");
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printf("%s: %s %s\n", name, out, datatype);
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}
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return 0;
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}
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void dcl(void)
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{
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int ns;
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for (ns = 0; gettoken() == '*';)
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ns++;
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dirdcl();
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while (ns-- > 0)
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strcat(out, " pointer to");
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}
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void dirdcl(void)
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{
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int type;
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if (tokentype == '(') {
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dcl();
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if (tokentype != ')')
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printf("error: missing )\n");
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} else if (tokentype == NAME)
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strcpy(name, token);
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else
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printf("error: expected name or (dcl)\n");
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while ((type = gettoken()) == PARENS || type == BRACKETS)
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if (type == PARENS)
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strcat(out, " function returning");
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else {
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strcat(out, " array");
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strcat(out, token);
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strcat(out, " of");
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}
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}
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int gettoken(void)
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{
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int c, getch(void);
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void ungetch(int);
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char *p = token;
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while ((c = getch()) == ' ' || c == '\t')
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;
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if (c == '(') {
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if ((c = getch()) == ')') {
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strcpy(token, "()");
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return tokentype = PARENS;
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} else {
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ungetch(c);
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return tokentype = '(';
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}
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} else if (c == '[') {
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for (*p++ = c; (*p++ = getch()) != ']'; )
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;
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*p = '\0';
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return tokentype = BRACKETS;
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} else if (isalpha(c)) {
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for (*p++ = c; isalnum(c = getch()); )
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*p++ = c;
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*p = '\0';
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ungetch(c);
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return tokentype = NAME;
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} else {
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return tokentype = c;
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}
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}
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int isvalid_datatype(const char* s)
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{
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char *datatypes[DATATYPE_LEN] = { "char", "short", "int", "long", "float", "double" };
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int len = 0;
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while (len < DATATYPE_LEN)
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if (strcmp(s, datatypes[len++]) == 0)
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return 1;
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return 0;
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}
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‎chapter-5-pointers-and-arrays/44.undcl.c‎

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/*
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* Exercise 5-19. Modify undcl so that it does not add redundant parentheses to declarations.
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* undcl: convert word description to declaration
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*
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* e.g.
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* x * int -> int *x
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* argv * * char -> char **argv
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* daytab * [] int -> int (*daytab)[]
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* daytab [] * int -> int *daytab[]
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* comp () * void -> void *comp()
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* comp * () void -> void (*comp)()
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* x () * [] * () char -> char (*(*x())[])()
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* x [] * () * [] char -> char (*(*x[])())[]
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*/
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#include <stdio.h>
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#include <string.h>
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#define MAXTOKEN 100
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enum { NAME, PARENS, BRACKETS };
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int gettoken(void);
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int tokentype; // type of last token
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char token[MAXTOKEN]; // last token string
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char out[1000]; // output string
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// gcc 44.undcl.c getch.c
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// cat 44.undcl.test | ./a.out
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main()
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{
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int type;
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char temp[MAXTOKEN];
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while (gettoken() != EOF) {
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strcpy(out, token);
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while ((type = gettoken()) != '\n') {
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if (type == PARENS) {
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if (out[0] == '*') {
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sprintf(temp, "(%s)", out);
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strcpy(out, temp);
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}
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strcat(out, token);
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} else if (type == BRACKETS) {
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if (out[0] == '*' || strstr(out, "()") != NULL) {
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sprintf(temp, "(%s)", out);
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strcpy(out, temp);
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}
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strcat(out, token);
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} else if (type == '*') {
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sprintf(temp, "*%s", out);
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strcpy(out, temp);
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} else if (type == NAME) {
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sprintf(temp, "%s %s", token, out);
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strcpy(out, temp);
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} else
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printf("invalid input at %s\n", token);
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}
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printf("%s\n", out);
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}
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return 0;
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}
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int gettoken(void)
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{
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int c, getch(void);
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void ungetch(int);
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char *p = token;
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while ((c = getch()) == ' ' || c == '\t')
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;
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if (c == '(') {
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if ((c = getch()) == ')') {
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strcpy(token, "()");
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return tokentype = PARENS;
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} else {
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ungetch(c);
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return tokentype = '(';
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}
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} else if (c == '[') {
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for (*p++ = c; (*p++ = getch()) != ']'; )
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;
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*p = '\0';
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return tokentype = BRACKETS;
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} else if (isalpha(c)) {
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for (*p++ = c; isalnum(c = getch()); )
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*p++ = c;
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*p = '\0';
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ungetch(c);
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return tokentype = NAME;
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} else {
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return tokentype = c;
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}
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}
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‎chapter-5-pointers-and-arrays/44.undcl.test‎

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x * int
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argv * * char
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daytab * [] int
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daytab [] * int
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comp () * void
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comp * () void
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x () * [] * () char
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x [] * () * [] char

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