code prints white spaces inside a string - c

Question

i have the next code, in which i have a string "hello world" and it has to convert each character into its ASCII value, but instead of printing [68656C.....] it prints some white spaces right after the '[', like this [......68656C]. And i can´t find the reason why
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
int i,lon;
char *cod_maq,*c = {"hello world"},c[2];
lon = strlen(c);
cod_maq = (char*)malloc((lon+1)*sizeof(char));
for(i = 0;i < lon;i++)
{
sprintf(c,"%X",c[i]);
strcat(cod_maq,c);
}
printf("[%s]\n",cod_maq);
return 0;
}
thanks

Answer 1

The memory in your malloc already contains data that you need to reset.
malloc allocates memory it doesn't initialize it, so you just get random garbage that was there previously.
memset(cod_maq, 0, size_of_cod_maq)

Answer 2

sprintf(c,"%X",c[i]); : very bad.
fix to like this:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(){
int i,lon;
char *cod_maq, *c = {"hello world"};
lon = strlen(c);
cod_maq = (char*)malloc((lon*2 + 1) * sizeof(char));//2 required per character
for(i = 0; i < lon; i++){
sprintf(cod_maq + i*2, "%02X", c[i]);
}
printf("[%s]\n", cod_maq);
free(cod_maq);
return 0;
}