Write a C++ program which capitalizes the first letter of each word in a sentence entered by the user

Question

I wrote the following C++ program to capitalize the first letter of each word in a sentence entered by the user:

#include <iostream>
#include <string>
using namespace std;

int main() 
{
  char Intstr[255];
  char Outstr[255];
  fgets(Intstr,255,stdin);
  
  int i = 0;
  Outstr[0] = toupper(Intstr[0]);
  for (i = 1; Intstr[i]; i++)
  {
    if (Intstr[i-1]==' ')
    {
      Outstr[i]=toupper(Intstr[i]);
    }
    else
    {
      Outstr[i]=Intstr[i];
    }
  }
  cout << Outstr << endl;
  
  return 0;
}

When I entered "hello world" into the command line, the expected output is "Hello World". However, the actual output is

Hello World╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠hello world

How can I fix this code so that the output is "Hello World"?

You need to add the `\0` in `Outstr` since you break the loop before doing so. — Holt, Jul 17 '21 at 17:00
Specifically, you stop the loop when you encounter the `\0`, but you never run an iteration of the loop for it. — , Jul 17 '21 at 17:02
Any [decent book](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list) should tell you to use `std::string` for all your strings. And that otherwise they are really called ***null-terminated** strings*. — Some programmer dude, Jul 17 '21 at 17:04
Does this answer your question? [What is a null-terminated string?](https://stackoverflow.com/questions/2037209/what-is-a-null-terminated-string) — Sreeraj Chundayil, Jul 17 '21 at 17:24

Gabriel Staples · Accepted Answer · 2021-07-20T16:21:59.117

The Intstr[i]; condition of the for loop stops the loop before it copies the null terminator (AKA: '\0', or just 0). So, add this one line after the for loop to copy the null terminator to the output C-string too.

  } // end of for loop
  Outstr[i] = Instr[i]; // copy the null-terminator too  <== ADD THIS LINE
  cout << Outstr << endl;

Remember, raw C-strings, unlike C++ std::string class objects, must always end in a null-terminator in order to mark where they end.

Otherwise, printing or using them will print whatever it finds from the start of the string to the first null-terminator it finds, which could be well-outside your C-string. All of the stuff read and printed outside of your C-string is a result of "undefined behavior", meaning the C and C++ standards make no guarantee of what will happen or what will be printed there. Usually, you get garbage characters from whatever happened to be sitting in memory there.

Your answer solves my problem and helps me get the desired output. Thank you so much! — YuanLinTech, Jul 17 '21 at 17:14

Write a C++ program which capitalizes the first letter of each word in a sentence entered by the user

1 Answers1

Linked