Santhosh Kumar Santhosh Kumar - 1 year ago 110
C++ Question

Case insensitive standard string comparison in C++

std::string str1 = "abracadabra";
std::string str2 = "AbRaCaDaBra";

if (! {
cout << "Compares"

How can I make this work? Bascially make the above case insensitive. Related question
I Googled and here

there is a case insensitive method String::Compare(str1, str2, Bool). Question is how is that related to the way I am doing.

Answer Source

You can create a predicate function and use it in std::equals to perform the comparison:

bool icompare_pred(unsigned char a, unsigned char b)
    return std::tolower(a) == std::tolower(b);

bool icompare(std::string const& a, std::string const& b)
    if (a.length()==b.length()) {
        return std::equal(b.begin(), b.end(),
                           a.begin(), icompare_pred);
    else {
        return false;

Now you can simply do:

if (icompare(str1, str)) {
    std::cout << "Compares" << std::endl;
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