C Library String Functions

You can access the builtin C library functions through header files. The string related functions are located in String.h file.

Each function listed below has a specific purpose.

Function	Description
strlen()	To find the length of a string.
strlwr()	Converts a string to lowercase.
strupr()	Converts a string to uppercase.
strcat()	Add one string to another to make a bigger string.
strncat()	Add n character of a string to another string
strcpy()	Copies a string to another string replaces any existing.
strcmp()	Compare two strings.
strncpy()	Copies first n characters of two strings.
strncmp()	Compares only first n characters with another string.
stricmp()	Compare two strings, disregards case.
strcmpi()	Same as stricmp()
strncmp()	Compares first n characters of two strings.
strnicmp()	Compares first n characters of two strings, disregards case
strdup()	Duplicate a string.
strchr()	Finds first occurrence of a given character in a string.
strrchr()	Finds last occurrence of a given character in a string.
strstr()	Finds first occurrence of a given string in another string.
strset()	Changes all characters of a string to given character.
strnset()	Changes first n char of a string to given character.
strrev()	Reverse a given string.

From the above table, , , and are the most frequently used functions.

C Library String Functions Example

You will write a program that implement these built-in functions.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
    char str[] = "Chile";
    char str2[] = "India";
    int len1;
    int len2;
    int boo;
  
/* Implement strlen() function */
    len1 = strlen(str);
    len2 = strlen(str2);
    printf("Length of First String = %d\n",len1);
    printf("Length of Second String = %d\n",len2);
    boo = strcmp(str2,str);
  
    if(boo > 0)
    {
        printf("String Mismatch\n");
    }
    else
    {
        printf("String Matched\n");
    }
  
    strcat(str,str2);
    printf("string cat = %s\n",str);
    strcpy(str,str2);
    printf("string copy = %s\n",str);
  
system("PAUSE"); 
return 0;
}

Output

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Length of First String = 5
Length of Second String = 5
String Mismatch
string cat = ChileIndia
string copy = India
Press any key to continue . . .