(C++) Convert a std::string to upper case

• The for-loop way
• The STL algorithm way

The for-loop way

include <string>

//#include <cstdlib>    // std::toupper
include <cctype>       // std::toupper


//Indeed, myString needs to be a copy of the original string
std::string StringToUpper(std::string myString)
{
  const int length = myString.length();
  for(int i=0; i!=length ; ++i)
  {
    myString[i] = std::toupper(myString[i]);
  }
  return myString;
}

The STL algorithm way

include <algorithm>

include <cctype>       // std::toupper

include <string>


int main()
{
  // explicit cast needed to resolve ambiguity
  std::transform(myString.begin(), myString.end(), myString.begin(),
               (int(*)(int)) std::toupper);
}

Other code snippets

Code links

• #include
• algorithm (header file)
• cctype (header file)
• include
• int
• main
• string
• string (header file)
• std
• std::transform

References

• 1) Bjarne Stroustrup. The C++ Programming Language (3rd edition).ISBN: 0-201-88954-4. Chapter 18.12.1: 'Prefer algorithms to loops]].
• 2) Scott Meyers. Effective STL. ISBN: 0-201-74962-9. Item 43: 'Prefer algorithm calls over hand-written loops'