c++ formating error with cstrings when using tolower

Question

Hi so I am trying to take a cstring and make it lowercase, but when I am printing the cstring at the end I am getting a weird format box where some of the letters should be. Do anyone have any ideas?

#include <string>
#include <iostream>
#include <string.h>

using namespace std;

int main () 
{ 
    int i=0; 
    char* str="TEST"; 
    char c; 
    char* cstr = new char[strlen(str) + 1];
    while (str[i]) 
    { 
        c = str[i]; 
        c = tolower(c);
        strcat(cstr, &c); 
        i++; 
    } 

    cout << cstr << endl; 
    return 0; 
}

Answer 1

The problem is that you are calling strcat incorrectly. The second parameter is not a null-terminated string.

You really don't need to call strcat at all. Just write directly to the output string:

Try:

  while (str[i])
  {
    c = str[i];
    c = tolower(c);
    cstr[i] = c;
        i++;
  }
  cstr[i] = 0;

or, equivalently:

while(str[i])
{
  cstr[i] = tolower(str[i]);
  i++;
}
cstr[i] = 0;