concat.c

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


char * concat (char *str, ...) { //note: nelze (...)
  size_t len;
  char *pch, *result;
  va_list args;
//co delat pokud str==NULL?
  if (NULL==str)
     return strdup("");
//1. pruchod spocitame delku
  len = strlen(str);
  va_start(args, str);
  while (pch = va_arg(args, char *)) {
    len += strlen(pch);
  }
  result = (char*)malloc(len+1);
//va_end(args);//musime pred novym va_start()?
//2. pruchod, append-ujeme
  va_start(args, str);
  strcpy(result, str);
  while (pch = va_arg(args, char *)) {
    strcat(result, pch);
  }
  va_end(args);
  return result;
}

int main(void) {
  printf("concat(\"a\",\"b\"...NULL): \"%s\"\n", concat("a","b","c",NULL));
  return 0;
}