how to implement the string handling functions. is it necesary to include any libraries. give example on string concatnation

Question

main()
{
    char a,b
    a='A';
    b='B';
    strcat(b,a);
    printf("a:%s b:%s",a,b);
}

Answer 1

You can start by learning basic C (especially pointers, arrays, and managing memory with malloc).

http://en.wikipedia.org/wiki/Strcat

Answer 2

The char type only holds a single character. To hold a string, you need an array of characters. In C, arrays are fixed in size, so the programmer must ensure that a character array has enough space to hold the string you want to put in it.

#include <stdio.h> //for printf    
#include <string.h> //for strncat

#define A_SIZE 10

int main(void)
{
    char a[A_SIZE] = "A";
    char b[] = "B";
    strncat(a, b, A_SIZE - strlen(a) - 1);
    printf("a:%s b:%s\n", a, b);
}