Convert a string to uppercase or lower case in C++.

Question

In one video, I saw that to convert a string to uppercase(with the data type char) you can use the function strupr(), or strlwr() (to lowercase) but!... I found in the internet that these both functions aren't standard (because of that, is not recommended to use it).
so... how can I convert a string (char or string data type) to uppercase or lowercase without using those non standard functions? I found that you can use toupper() or tolower(), but it only works with char data type. I want to use string too.

Answer 1

Eduardo Perez Regin there is a toupper in global namespace also... you can use it as follow to convert string directly to upper case:

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

int main()
{
string str = "asd";
transform(str.begin(),str.end(),str.begin (),::toupper);
cout << str << endl;

return 0;
}

Answer 2

with toupper() and tolower() you can use a for loop to go threw your string and make them all uppercase or lowercase.

Answer 3

Mooaholic but only works with char data type right? what about if my string is a string data type? in that case you cannot use toupper() and tolower(), right? when you are receiving a string, should I use char data type or string data type?

Answer 4

you can use a forloop so if you have
string a = “test”;
and your want to make that uppercase you can use
for(int i = 0; i < a.size(); i++){
a[i] = toupper(a[i]);
}
this will go threw each char of the string test and make it TEST.

Answer 5

thx to everyone!!