Question

  I have a file copy program that takes from one file and pastes in another file pointer. But, instead of getting targetname from user input i’d like to just add a ‘1’ at the end of the input filename and save. So, I tried something like this…

       .... header & inits ....
       fp=fopen(argv[1],"r");
       fq=fopen(argv[1].'1',"w");
       .... file copy code ....

Yeah it seems stupid but I’m a beginner and need some help, do respond soon. Thanks 😀

P.S. Want it in pure C. I believe the dot operator can work in C++.. or atleast i think.. hmm

One more thing, i’m already aware of strcat function.. If i use it, then i’ll have to define the size in the array… hmm. is there no way to do it like fopen(argv[1]+”extra”,”w”)

Answer 1

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

char* stradd(const char* a, const char* b){
    size_t len = strlen(a) + strlen(b);
    char *ret = (char*)malloc(len * sizeof(char) + 1);
    *ret = '\0';
    return strcat(strcat(ret, a) ,b);
}

int main(int argc, char *argv[]){

    char *str = stradd(argv[1], "extra");

    printf("%s\n", str);

    free(str);

    return 0;
}