Home » C programs » C Strings User-defined Functions Programs

C program to compare two string using case and ignoring case without using library function

Problem statement

In this program, we will learn how to compare two strings without using library function using case and ignoring case sensitivity.

Implementing stringCmp() and stringCmpi() functions in C

Here, we will read two string (that can contains spaces too) and compares them using following two function,

1. stringCmp() - Compares two strings (case sensitive).
2. stringCmpi() - Compares two string ignoring case.

Program to compare two strings without using library function in C

#include <ctype.h>
#include <stdio.h>

/********************************************************
    *   function name       :stringCmp, stringCmpi
    *   Parameter           :char* s1,char* s2
    *   Return              :0- success, 1- fail
    *   Description
        stringCmp   - compares two strings
        stringCmpi  - compares two string (ignoring case)
********************************************************/
int stringCmp(char *s1, char *s2);
int stringCmpi(char *s1, char *s2);

int main() {
  char str1[100], str2[100];

  printf("Enter  string 1 : ");
  scanf("%[^\n]s", str1);  // read string with spaces

  getchar();  // to read enter after first string

  printf("Enter  string 2 : ");
  scanf("%[^\n]s", str2);  // read string with spaces

  if (!stringCmp(str1, str2))
    printf("\n stringCmp  :String are same.");
  else
    printf("\n stringCmp  :String are not same.");

  if (!stringCmpi(str1, str2))
    printf("\n stringCmpi :String are same.");
  else
    printf("\n stringCmpi :String are not same.");

  printf("\n");
  return 0;
}

/******** function definition *******/
int stringCmp(char *s1, char *s2) {
  int i = 0;
  for (i = 0; s1[i] != '\0'; i++) {
    if (s1[i] != s2[i]) return 1;
  }
  return 0;
}

/******** function definition *******/
int stringCmpi(char *s1, char *s2) {
  int i = 0, diff = 0;
  for (i = 0; s1[i] != '\0'; i++) {
    if (toupper(s1[i]) != toupper(s2[i])) return 1;
  }
  return 0;
}

Output

Enter  string 1 : includehelp
Enter  string 2 : IncludeHelp

stringCmp  :String are not same.
stringCmpi :String are same.

C Strings User-defined Functions Programs »