I am sorry, donot use my first message.......
There are some currections......
use this........
prototype:
char* strcat(char *str1,char *str2);
but here 'str1' should be big enough, so that the resultant string can fit in.
char* strcat(char *str1,char *str2) {
int i;
int j;
for(i=strlen(str1),j=0;str2[j]!='\0';i++,j++)
str1 = str2[j];
str1 = '\0';
}