C++: error: no matching function for call to 'f(int, const char*)'

Meaning

GCC lists every candidate and why it was rejected ("candidate expects 2 arguments, 1 provided", "no known conversion from ..."). Read the first candidate that looks like what you meant. For constructors the message says no matching function for call to 'X::X(...)'.

Common causes

• Wrong number of arguments
• Argument type has no implicit conversion to the parameter type
• Passing a temporary to a non-const reference parameter
• Template deduction failed because arguments disagree (for example int and double)
• Function declared in a different namespace or not yet declared

Detailed fix by platform

Code examples

void scale(double& factor);          // takes a non-const reference

int main() {
    // scale(2.0);                   // error: no matching function (cannot bind rvalue)
    double f = 2.0;
    scale(f);                        // OK
}
// or declare: void scale(const double& factor);

How to diagnose

1. Count — Same number of arguments as the candidate?
2. Types — Which "no known conversion" line applies?
3. Reference — Is a temporary passed to T&?

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