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level03.c
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level03.c
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#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#define NUM_FNS 4
typedef int (*fn_ptr)(const char *);
int to_upper(const char *str)
{
printf("Uppercased string: ");
int i = 0;
for (i; str[i]; i++)
putchar(toupper(str[i]));
printf("\n");
return 0;
}
int to_lower(const char *str)
{
printf("Lowercased string: ");
int i = 0;
for (i; str[i]; i++)
putchar(tolower(str[i]));
printf("\n");
return 0;
}
int capitalize(const char *str)
{
printf("Capitalized string: ");
putchar(toupper(str[0]));
int i = 1;
for (i; str[i]; i++)
putchar(tolower(str[i]));
printf("\n", str);
return 0;
}
int length(const char *str)
{
int len = 0;
for (len; str[len]; len++) {}
printf("Length of string '%s': %d\n", str, len);
return 0;
}
int run(const char *str)
{
// This function is now deprecated.
return system(str);
}
int truncate_and_call(fn_ptr *fns, int index, char *user_string)
{
char buf[64];
// Truncate supplied string
strncpy(buf, user_string, sizeof(buf) - 1);
buf[sizeof(buf) - 1] = '\0';
printf("fns in truncate=%p\n", &fns[0]);
printf("&buf[0] = %p\n", &buf[0]);
printf("&fns[%d] - &buf[0] = %d\n", index, (char*)&fns[index] - (char*)&buf[48]);
printf("*fns[%d] = %p\n", index, (fn_ptr*)fns[index]);
return fns[index](buf);
}
int main(int argc, char **argv)
{
int index;
fn_ptr fns[NUM_FNS] = {&to_upper, &to_lower, &capitalize, &length};
if (argc != 3) {
printf("Usage: ./level03 INDEX STRING\n");
printf("Possible indices:\n[0] to_upper\t[1] to_lower\n");
printf("[2] capitalize\t[3] length\n");
exit(-1);
}
printf("%p\n", &index);
printf("%p\n", fns);
printf("&argv = %p\n", &argv);
printf("&index = %p\n", &index);
printf("&run() = %p\n", run);
printf("&argv[2] = %p\n", argv[2]);
// Parse supplied index
index = atoi(argv[1]);
if (index >= NUM_FNS) {
printf("Invalid index.\n");
printf("Possible indices:\n[0] to_upper\t[1] to_lower\n");
printf("[2] capitalize\t[3] length\n");
exit(-1);
}
return truncate_and_call(fns, index, argv[2]);
}