Inbuilt function for String Processing :-

NOTE : All Inbuilt Function of String need string.h library.

1. strcpy(Target_String , Source_String ) :-

This function will take 2 string as argument one is Target_String and another is Source_String, this function will copy Source_String into Target_String. e.g.

#include<stdio.h>
#include<string.h>
int main()
{
	char A[15] = "Vipin Yadav";
	char B[15] = "- - - - -";

	printf("Value of A and B before calling function. nn");
	puts(A);
	puts(B);

	strcpy(B,A);
  // It will copy A in B as you can see in Output.

	printf("nValue of A and B after calling function. nn");
	puts(A);
	puts(B);

  return 0;
}

Output:-

Value of A and B before calling function. 

Vipin Yadav
- - - - -

Value of A and B after calling function. 

Vipin Yadav
Vipin Yadav

2. strncpy(Target_String , Source_String ) :-

This function will take 2 string as argument one is Target_String and another is Source_String, just like strcpy() this function will copy n letters from Source_String into Target_String, and it do not affect reaming part of string. e.g.

#include<stdio.h>
#include<string.h>
int main()
{
	char A[15] = "Vipin Yadav";
	char B[15] = "- - - - -";

	printf("Value of A and B before calling function. nn");
	puts(A);
	puts(B);

	strncpy(B,A,5);
  // It will copy A in B but upto n characters and don't disturb other values of B.

	printf("nValue of A and B after calling function. nn");
	puts(A);
	puts(B);

  return 0;
}

Output:-

Value of A and B before calling function. 

Vipin Yadav
- - - - -

Value of A and B after calling function. 

Vipin Yadav
Vipin - -

3. strcat(Target_String , Source_String ) :-

This function is used to concatenate Source_String just after Target_String or we can say to append Source_String with Target_String.

e.g.

#include<stdio.h>
#include<string.h>
int main()
{
	char A[20] = " Vipin Yadav";
	char B[20] = "-";

	printf("Value of A and B before calling function. nn");
	puts(A);
	puts(B);

	strcat(B,A);
	// It will append B with A

	printf("nValue of A and B after calling function. nn");
	puts(A);
	puts(B);

  return 0;
}

Output:-

Value of A and B before calling function. 

 Vipin Yadav
-

Value of A and B after calling function. 

 Vipin Yadav
- Vipin Yadav

4. strncat(Target_String , Source_String ) :-

This function is used to concatenate Source_String just after Target_String or we can say to append Source_String, with Target_String but here we can limit that how much letters you want to append.

e.g.

#include<stdio.h>
#include<string.h>
int main()
{
	char A[20] = " Vipin Yadav";
	char B[20] = "-";

	printf("Value of A and B before calling function. nn");
	puts(A);
	puts(B);

	strncat(B,A,5);
	// It will append B with A upto 5 le tters

	printf("nValue of A and B after calling function. nn");
	puts(A);
	puts(B);

  return 0;
}

Output:-

Value of A and B before calling function. 

 Vipin Yadav
-

Value of A and B after calling function. 

 Vipin Yadav
- Vipi    ( Don't mess with ' ' before V :;)

5. strcmp( First_String , Second_String ) :-

This function will take 2 Stings as argument and return a>;0 value if First_String is, greater( not on the basic of length :) ) and return <0 if Second_String is greater and return 0 If both are Equal.

NOTE : strcmp() IS CASE SENSITIVE e.g.

#include<stdio.h>
#include<string.h>
int main()
{
	char A[20] = "aaaa";
	char B[20] = "AAAA";
	int x;

	x = strcmp(A,B);

	if ( x == 0 )
		printf("Both Stings are Equal.");
	else if ( x == 1 )
		printf("First Stings is greater.");
	else // mean strcmp() return -1
		printf("Second Stings is greater.");

  return 0;
}

Output:-

Second Stings is greater.

5. stricmp( First_String , Second_String ) or strcmpi( First_String , Second_String ) :-

This function will take 2 Stings as argument and return a>;0 value if First_String is, greater( not on the basic of length :) ) and return <0 if Second_String is greater and return 0 If both are Equal.

NOTE : stricmp() or strcmpi() IS NOT CASE SENSITIVE AND THIS FUNCTION IS NOT FROM STANDERD LIBRARY OF C             LANGUAGE   SO IT WILL NOT WORK IN SOME COMPILERS LIKE IN LINUX/UNIX . e.g.

#include<stdio.h>
#include<string.h>
int main()
{
    char A[20] = "aaaa";
    char B[20] = "AAAA";

    int x;

    x = strcmpi();

    if ( x == 0 )
        printf("Both Stings are Equal.");
    else if ( x == 1 )
        printf("First Stings is greater.");
    else // mean strcmp() return -1
        printf("Second Stings is greater.");
    
    return 0;
}

Output:-

Both Stings are Equal.

6. strlen( String ) :-

This function will take a String as argument and return it’s length.

e.g.

#include<stdio.h>
#include<string.h>
int main()
{
    char A[20] = "aaaa";

    int x;

    x = strlen(A);
    
    printf("Length of A is %d.",x);

    return 0;
}

Output:-

Length of A is 4.

7. strlwr( String ) :-

This function of C language will convert all alphabets of String in lowercase.

NOTE: THIS FUNCTION IS NOT FROM STANDARD LIBRARY OF C LANGUAGE SO IT WILL NOT WORK IN SOME COMPILERS LIKE IN LINUX/UNIX .

e.g.

#include<stdio.h>
#include<string.h>
int main()
{
    char A[20] = "AAAA";

    strlwr(A);
    
    puts(A);

    return 0;
}

Output:-

aaaa

8. strupr( String ) :-

This function of C language will convet all alphabets of String in uppercase.

NOTE: THIS FUNCTION IS NOT FROM STANDARD LIBRARY OF C LANGUAGE SO IT WILL NOT WORK IN SOME COMPILERS LIKE IN LINUX/UNIX . e.g.

#include<stdio.h>
#include<string.h>
int main()
{
    char A[20] = "aaaa";

    strupr(A);
    
    puts(A);

    return 0;
}

Output:-

AAAA

9. strset( String , character ) :-

This function will change hole string with a character you give, means It take 2 argument a string and a character and replace hole string with that character.

e.g.

#include<stdio.h>
#include<string.h>
int main()
{
    char A[20] = "Vipin";
    char C = 'V';

    strset(A,C);
    
    puts(A);

    return 0;
}

Output:-

VVVVV

10. strnset( String , character , n ) :-

This function will change hole string with a character you give but upto a limit, means It take 3 argument a string and a character and a integer and replace hole string with that character, till n .

e.g.

#include<stdio.h>
#include<string.h>
int main()
{
    char A[20] = "Vipin";
    char C = 'V';

    strnset(A,C,3);
    
    puts(A);

    return 0;
}

Output:-

VVVin

11. strspm( String1 , String2 ) :-

This function will take 2 string as argument and return the number of characters in the initial segment of String1 which consist only of characters from String2.

e.g.

#include<stdio.h>
#include<string.h>
int main()
{
    char A[] = "Vipin is my name";
    char C[] = "Vipin";
    int x;

    x = strspn(A,C);
    
    printf("String C matches In String A till %d.",x);

    return 0;
}

Output:-

String C matches In String A till 5.

One function is there name strstr() we will learn it when we learn about pointers.