Write a program to concatenat e two strings without using strcat() function.

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15.Write a program to concatenat e two strings without using strcat() function.

strcat(str ing1,strin g2) is a C standard function declared in the header file string.h

The strcat() function concatenat es string2, string1 and returns string1.

Program: Program to concatenat e two strings

#include

#include

char *strct(cha r *c1, char *c2);

char *strct(cha r *c1, char *c2){

//strlen function returns length of argument string

int i = strlen(c1) ;

int k = 0;

// loops until null is encountered and appends string c2 to c1

while (c2[k] !='\0'){

c1[i + k] = c2[k];

k++;

}

return c1;

}

int main(){

char string1[15 ] ="first";

char string2[15 ] ="second";

char *finalstr;

printf("Be fore concatenat ion:"

"\n string1 = %s \n string2 = %s", string1, string2);

// addresses of string1, string2 are passed to strct()

finalstr = strcat(str ing1, string2);

printf("\n After concatenat ion:");

//prints the contents of string whose address is in finalstr

printf("\n finalstr = %s", finalstr);

//prints the contents of string1

printf("\n string1 = %s", string1);

//prints the contents of string2

printf("\n string2 = %s", string2);

return 0;

}

Output:

Before concatenat ion:

string1 = first

string2 = second

After concatenat ion:

finalstr = firstsecon d

string1 = firstsecon d

string2 = second

Explanatio n:

string2 is appended at the end of string1 and contents of string2 are unchanged.

In strct() function, using a for loop, all the characters of string'c2'are copied at the end of c1. return (c1) is

equivalent to return&c1[0] and it returns the base address of'c1'.'finalstr' stores that address returned by the

function strct().