How to change all strings in vector to uppercase?

Question

I am trying to get a sequence of words from cin and store the values in a vector. After I’ve read all the words, I want to process the vector and change each word to uppercase.

This is my code:

#include<iostream>
#include<string>
#include<cctype>
#include<vector>

using namespace std;

int main() {
    string line;
    vector<string> words;
    while( getline(cin, line) ) {
        words.push_back(line);
    }
    for (auto &c : words) {
        c = toupper(c);
        cout << c << endl;
    }
}

I am getting error at the c = toupper(c):

||=== Build: Debug in test (compiler: Cygwin GNU GCC Compiler) ===|
C:\Users\Ajay\Desktop\test\test\main.cpp||In function â€˜int main()â€™:|
C:\Users\Ajay\Desktop\test\test\main.cpp|15|error: no matching function for call to â€˜toupper(std::basic_string<char>&)â€™|
C:\Users\Ajay\Desktop\test\test\main.cpp|15|note: candidates are:|
\usr\include\ctype.h|20|note: int toupper(int)|
\usr\include\ctype.h|20|note:   no known conversion for argument 1 from â€˜std::basic_string<char>â€™ to â€˜intâ€™|
\usr\lib\gcc\i686-pc-cygwin\4.8.2\include\c++\bits\locale_facets.h|2596|note: template<class _CharT> _CharT std::toupper(_CharT, const std::locale&)|
\usr\lib\gcc\i686-pc-cygwin\4.8.2\include\c++\bits\locale_facets.h|2596|note:   template argument deduction/substitution failed:|
C:\Users\Ajay\Desktop\test\test\main.cpp|15|note:   candidate expects 2 arguments, 1 provided|
||=== Build failed: 1 error(s), 0 warning(s) (0 minute(s), 0 second(s)) ===|

Would be faster to find the bug if you were actually posting the error. That said, I will be right back with the solution. — Emz, Jan 26 '14 at 12:55
This nice example why the C++11 `auto` keyword is not always a nice feature. — hetepeperfan, Jan 26 '14 at 12:57
I think `&c : words` reads as **for every character in words**. — ajknzhol, Jan 26 '14 at 13:00
@ajkumar25 the container `words` is a vector of `std::string`, so `c` references to elements of vector i.e. `std::string` not _char_ — P0W, Jan 26 '14 at 13:02
@Dave `for (auto & c: str) c = toupper(c);` is also present in your link. — ajknzhol, Jan 26 '14 at 13:02
@ajkumar25 that's kind of hetepeperfan's point; auto in your code is referring to a string, but in that example it is a char. Don't use auto except for extreme circumstances. — Dave, Jan 26 '14 at 13:04
Obligatory: you cannot convert a word to uppercase without knowing what language it is written in. — n. m. could be an AI, Jan 26 '14 at 13:09
This question is asking how to change every string in a vector. The duplicate shows how to change just a single string. I'm reopening this question. — cigien, Dec 07 '20 at 02:39

BLUEPIXY · Accepted Answer · 2014-01-26T13:08:50.457

2

    for(auto &word : words){
        for (auto &c : word) {
            c = ::toupper(c);
            cout << c << endl;
        }
    }

edited Jan 26 '14 at 13:08

answered Jan 26 '14 at 13:03

BLUEPIXY

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You probably need a reference for `word` too – P0W Jan 26 '14 at 13:06
This code has undefined behavior if `char` is signed in the implementation and any of the characters in the string has the top bit set. – Steve Jessop Jan 26 '14 at 14:00

How to change all strings in vector to uppercase?

1 Answers1