chapter 7 sample code

Author: Heatwave

chapter-7-input-and-output/cat-v1.c

@@ -0,0 +1,30 @@
+#include <stdio.h>
+
+main(int argc, char *argv[])
+{
+	FILE *fp;
+	void filecopy(FILE *, FILE *);
+
+	if (argc == 1)
+		filecopy(stdin, stdout);
+	else
+		while (--argc > 0)
+			if ((fp = fopen(*++argv, "r")) == NULL) {
+				printf("cat: can't open %s\n", *argv);
+				return 1;
+			} else {
+				filecopy(fp, stdout);
+				fclose(fp);
+			}
+	
+	return 0;
+}
+
+void filecopy(FILE *ifp, FILE *ofp)
+{
+	int c;
+
+	while ((c = getc(ifp)) != EOF)
+		putc(c, ofp);
+}
+

chapter-7-input-and-output/cat-v2.c

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+main(int argc, char *argv[])
+{
+	FILE *fp;
+	void filecopy(FILE *, FILE *);
+	char *prog = argv[0];
+
+	if (argc == 1)
+		filecopy(stdin, stdout);
+	else
+		while (--argc > 0)
+			if ((fp = fopen(*++argv, "r")) == NULL) {
+				fprintf(stderr, "%s: can't open %s\n", prog, *argv);
+				exit(1);
+			} else {
+				filecopy(fp, stdout);
+				fclose(fp);
+			}
+
+	if (ferror(stdout)) {
+		fprintf(stderr, "%s: error writing stdout\n", prog);
+		exit(2);
+	}
+	
+	exit(0);
+}
+
+void filecopy(FILE *ifp, FILE *ofp)
+{
+	int c;
+
+	while ((c = getc(ifp)) != EOF)
+		putc(c, ofp);
+}
+

chapter-7-input-and-output/minprintf.c

@@ -0,0 +1,46 @@
+#include <stdarg.h>
+#include <stdio.h>
+
+void minprintf(char *fmt, ...);
+
+int main()
+{
+	minprintf("int: %d, double: %f, string: %s\n", 1, 0.123, "Hello");
+
+	return 0;
+}
+
+void minprintf(char *fmt, ...)
+{
+	va_list ap;
+	char *p, *sval;
+	int ival;
+	double dval;
+
+	va_start(ap, fmt);
+	for (p = fmt; *p; p++) {
+		if (*p != '%') {
+			putchar(*p);
+			continue;
+		}
+		switch(*++p) {
+		case 'd':
+			ival = va_arg(ap, int);
+			printf("%d", ival);
+			break;
+		case 'f':
+			dval = va_arg(ap, double);
+			printf("%f", dval);
+			break;
+		case 's':
+			for (sval = va_arg(ap, char *); *sval; sval++)
+				putchar(*sval);
+			break;
+		default:
+			putchar(*p);
+			break;
+		}
+	}
+	va_end(ap);
+}
+

chapter-7-input-and-output/scanf-sample.c

@@ -0,0 +1,12 @@
+#include <stdio.h>
+
+main()
+{
+	double sum, v;
+
+	sum = 0;
+	while (scanf("%1f", &v) == 1)
+		printf("\t%.2f\n", sum += v);
+	return 0;
+}
+