Problem with string pop_back() function

[frostmourne0529]

There is an error with the pop_back function in this case.
In this code finalpuncuation(string) is a bool function.

void dePuncuation(const std::string &word) {
	char c = word[0];
	if (('A' <= c) && (c <= 'Z'))
		c += ('a' - 'A');
	if (finalpuncuation(word))
		word.pop_back();
}

[TheIdeasMan]

Can you explain what const means? Also the effect of operator += on a char, and the value you pass to it?

[cire]

Compilation issues aside, something along these lines may be more appropriate:

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

std::string lowered(std::string s) {
    std::transform(s.begin(), s.end(), s.begin(), [](char c) { return std::tolower(c); });
    return s;
}

std::string unpunctuated(const std::string& s)
{
    std::string result;

    std::copy_if(s.begin(), s.end(), std::back_inserter<std::string>(result),
        [](char c) { return !std::ispunct(c); });

    return result;
}

// for convenience
std::string reformatted(const std::string& s) { return lowered(unpunctuated(s)); }

int main()
{
    std::string punctuated = "\"This is a (some-what) punctuated string!?!.**@#$\"";

    std::cout << "Original: " << punctuated << '\n';
    std::cout << "Modified: " << reformatted(punctuated) << '\n';
}

where each individual function has a clear job to do and each can be used independently of the other if so desired.