C String Functions

String Functions :

C also has many useful string functions, which can be used to perform certain operations on strings.

To use them, you must include the <string.h> header file in your program: 

String Length :

For example, to get the length of a string, you can use the strlen() function: 

#include <stdio.h>
#include <string.h>
 
int main() {
  char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  printf("%d", strlen(alphabet));
  return 0;
}

 हमने string/array का size  प्राप्त करने के लिए sizeof का उपयोग किया। ध्यान दें कि sizeof और strlen अलग-अलग व्यवहार करते हैं, क्योंकि गिनती करते समय sizeof में \0 character  भी शामिल होता है:

#include <stdio.h>
#include <string.h>
 
int main() {
  char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  printf("Length is: %d\n", strlen(alphabet));
  printf("Size is: %d\n", sizeof(alphabet));
  return 0;
}

यह भी महत्वपूर्ण है कि आप जानते हैं कि sizeof  हमेशा memory size (bytes में) लौटाएगा, न actual string length:

#include <stdio.h>
#include <string.h>
 
int main() {
  char alphabet[50] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  printf("Length is: %d\n", strlen(alphabet));
  printf("Size is: %d\n", sizeof(alphabet));
  return 0;
}

Concatenate Strings :

 two strings को जोड़ने (combine) के लिए, आप  strcat()  function  का  उपयोग कर सकते हैं:

#include <stdio.h>
#include <string.h>
 
int main() {
  char str1[20] = "Hello ";
  char str2[] = "World!";
  // Concatenate str2 to str1 (the result is stored in str1)
  strcat(str1, str2);
  
  // Print str1
  printf("%s", str1);
 
  return 0;
}

Note that the size of str1 should be large enough to store the result of the two strings combined (20 in our example)

Copy Strings :

एक string  के value  को दूसरे में copy  करने के लिए, आप  strcpy() function  का उपयोग कर सकते हैं:

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

int main() {
  char str1[20] = "Hello World!";
  char str2[20];
  // Copy str1 to str2
  strcpy(str2, str1);

  // Print str2
  printf("%s", str2);
  
  return 0;
}

Note that the size of str2 should be large enough to store the copied string (20 in our example).

Compare Strings :

To compare two strings, you can use the strcmp() function. 

यदि  two strings बराबर हैं तो यह 0 लौटाता है, अन्यथा वह value 0 नहीं है:

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

int main() {
  char str1[] = "Hello";
  char str2[] = "Hello";
  char str3[] = "Hi";
  // Compare str1 and str2, and print the result
  printf("%d\n", strcmp(str1, str2));
  
  // Compare str1 and str3, and print the result
  printf("%d\n", strcmp(str1, str3));
  
  return 0;
}