Question

I have programmed a self-made concat function:

char * concat (char * str1, char * str2) {
    for (int i=0; i<BUFSIZ; i++) {
        if (str1[i]=='\0') {
            for (int j=i; j<BUFSIZ; j++) {
                if (str2[j-i]=='\0') return str1;
                else str1[j]=str2[j-i];
            }
        }
    }
}

Now if I want to concat more than 2 strings, i.e. buf temp1 temp2,
I have to use something like that:

strcpy(buf, concat(concat(buf,temp1),temp2));

Please tell me, is there a simple way to modify my function so it would accept many arguments?

Answer 1

The feature you’re looking for is varargs. This allows you to write a C function which accepts a variable number of arguments. It’s how functions like printf are implemented

char* concat(size_t argCount, ...) {
  va_list ap;

  char* pFinal = ... // Allocate the buffer
  while (argCount) {
    char* pValue = va_arg(ap, char*);
    argCount--;

    // Concat pValue to pFinal

  }
  va_end(ap);

  return pFinal;
}

Now you can call concat with a variable number of arguments

concat(2, "hello", " world");
concat(4, "hel", "lo", " wo", "rld");