Initial commit

completed exercise.

Author: fsaadatmand

chapter07/7-6.c

@@ -0,0 +1,69 @@
+/*
+ * Exercise 7-6. Write a program to compare two file, printing the first line
+ * where they differ.
+ * By Faisal Saadatmand
+ */
+
+#define MAXFILES  3
+#define MAXLEN    1000
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* functions */
+int  getLine(FILE *, char *, int);
+
+/* getLine: read line, return length - fgets version */
+int getLine(FILE *fp, char *line, int max)
+{
+	if (fgets(line, max, fp) == NULL)
+		return 0;
+	else
+		return strlen(line);
+}
+
+int main(int argc, char *argv[])
+{
+	FILE *file[MAXFILES];                  /* array to store files */
+	char *prog = argv[0];                  /* program name for errors */
+	char *f1name = argv[1];                /* file 1 name for printing line */
+	char *f2name = argv[2];                /* file 2 name for printing line */
+	char f1line[MAXLEN], f2line[MAXLEN];   /* currently read line */
+	int  f1ln, f2ln;                       /* currently read line number */
+	int  result, i;
+	
+	if (argc != 3) {                       /* wrong format */
+		fprintf(stderr, "Use: %s file1 file2\n", prog);
+		exit(EXIT_FAILURE);
+	}
+
+	/* open files */
+	for (i = 1; --argc > 0; ++i)           /* skip file[0] for readability */
+		if ((file[i] = fopen(*++argv, "r")) == NULL) {
+			fprintf(stderr, "%s: can't open %s\n", prog, *argv);
+			exit(EXIT_FAILURE);
+		}
+
+	f1ln = f2ln = result = 0;
+	while (!feof(file[1]) || !feof(file[2])) { 
+		if (getLine(file[1], f1line, MAXLEN) > 0)
+			f1ln++;                        /* count successfully read lines */
+		if (getLine(file[2], f2line, MAXLEN) > 0)
+			f2ln++;                        /* count successfully read lines */
+
+		if ((result = strcmp(f1line, f2line)) != 0)
+			break;                         /* found mismatching line */
+	}
+
+	if (result != 0) {
+		fprintf(stdout, "%s: %i: %s", f1name, f1ln, f1line);
+		fprintf(stdout, "%s: %i: %s", f2name, f2ln, f2line);
+	} else
+		printf("%s and %s are identical\n", f1name, f2name);
+
+	fclose(file[1]);
+	fclose(file[2]);
+
+	exit(EXIT_SUCCESS);
+}