Compare Files - C File

C examples for File:File Operation

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Description

Compare Files

Demo Code

#include <stdio.h>
#include <string.h>

#define MaxName 20/*from  ww w.j a  v  a2 s .c  o m*/
#define MaxLine 101

FILE *getFileName(char *, char *);

int main() {
  char name1[MaxName], name2[MaxName];
  char line1[MaxLine], line2[MaxLine];
  FILE *file1, *file2;
  char *eof1, *eof2;

  int lineNum = 0;
  file1 = getFileName("First file?", name1);
  file2 = getFileName("Second file?", name2);

  while (((eof1 = fgets(line1, MaxLine, file1)) != NULL) && ((eof2 = fgets(line2, MaxLine, file2)) != NULL) && (strcmp(line1, line2) == 0))
    lineNum++;
  if (eof1 == NULL) //first file ended
    if (fgets(line2, MaxLine, file2) == NULL) //second also ended
      printf("\nFiles are identical\n\n");
    else                 //first file ended, second file not ended
      printf("\n%s, with %d line(s), is a subset of %s\n", name1, lineNum, name2);
  else if (eof2 == NULL)  //first file not ended, second file ended
    printf("\n%s, with %d line(s), is a subset of %s\n", name2, lineNum, name1);
  else {               // mismatch found
    printf("\nThe files differ at line %d\n", ++lineNum);
    printf("The lines are \n%s and \n%s", line1, line2);
  }
  fclose(file1);
  fclose(file2);
}

FILE * getFileName(char *prompt, char *name) {
  FILE *filePtr;
  do {
    printf("%s ", prompt);
    gets_s(name,20);
    if ((filePtr = fopen(name, "r")) == NULL)
      printf("File does not exist or access denied\n");
  } while (filePtr == NULL);
  return filePtr;
}

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