How to convert lowercase characters of a string to uppercase characters in C++?

Question

I have a question where all lowercase characters of a string should be converted into uppercase characters.But as per the question, certain lines in the code should not be changed. I have written the code below.

 #include <iostream>
 #include <string>
 #include <stdio.h>
 #include <ctype.h>
 using namespace std;

 class StringOps {
 public:
   void stringToUpper(string &s) //This line should not be changed
  {
    char c;
    int i=0;
    while (s[i])
    {
     c=s[i];
     putchar (toupper(c));
     i++;
    }
  }
 };

 int main(void)
 {
   string str ="Hello World";  
   StringOps obj;
   obj.stringToUpper(str);
   cout << str;            //This line should not be changed
   return 0;
   }

I get the output as:

HELLO WORLDHello World

But the required output is:

HELLO WORLD HELLO WORLD

How do I make the

 cout<<str;

statement in main() to print the result computed in the function :

 void stringToUpper(string &s)

Well, it looks like you want to modify `s` in `stringToUpper`, rather than just read from it. — aschepler, Jun 03 '17 at 16:06
You should seek to make `stringToUpper` _change_ `s` instead of printing something like it is currently doing. — Drew Dormann, Jun 03 '17 at 16:06

Yuki · Answer 1 · 2017-06-03T16:32:47.507

0

Solution only for the lower part of ASCII characters.

class StringOps {
public:
  void stringToUpper(string& s) //This line should not be changed
  {
    for (size_t i = 0; i < s.size(); ++i) {
      if (s[i] > 96 && s[i] < 123)
        s[i] -= 32;
    }
  }
};

and if you care about the higher part of the ASCII table:

class StringOps {
public:
  void stringToUpper(string& s) //This line should not be changed
  {
    for (size_t i = 0; i < s.size(); ++i) {
      s[i] = toupper(s[i]);
    }
  }
};

If you have some multi-byte encoding, like UTF-8, you will need some library.

edited Jun 03 '17 at 16:32

answered Jun 03 '17 at 16:20

Yuki

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Thank you for your effort!! – Aanandhi V B Jun 03 '17 at 16:27

score 0 · Answer 2 · answered Jun 03 '17 at 16:30

cout << str; //This line should not be changed

This means that you must change str.

void stringToUpper(string &s) //This line should not be changed

Good news, your method take s as a reference.

In your code you are doing c=s[i]; you should reassign the char in your string s[i] = c

score 0 · Answer 3 · answered Jun 03 '17 at 16:38

You are just printing the string with making each character as upper character, but the string that passed to function (by reference) "s" does not get changed.

void stringToUpper(string &s)

A line can be added to make s to get changed in void stringToUpper(string &s)

 s[i] = toupper(c);

Code will look

 c=s[i];
 s[i] = toupper(c);
 putchar (toupper(c));
 i++;

Output will be

HELLO WORLDHELLO WORLD

How to convert lowercase characters of a string to uppercase characters in C++?

3 Answers3