C++: error: expected primary-expression before ')' token

Meaning

Typical triggers: passing a type to a function (foo(int)), an empty argument, a stray comma or ), or a macro that expands to nothing. GCC names the unexpected token in the message, so look at what precedes it.

Common causes

• A type name used where a value is expected (for example sizeof(x) written as size(int x))
• Missing argument between commas or before )
• Trailing comma in an argument or initializer list
• Macro that expands to an empty expression
• Mixing up declaration syntax and a function call

Detailed fix by platform

Code examples

int square(int n) { return n * n; }

int main() {
    // int r = square(int);          // error: expected primary-expression before 'int'
    int r = square(5);
    return r;
}

How to diagnose

1. Token — Which token does the message name?
2. Arguments — Are all argument slots filled?
3. Macros — Does a macro expand to nothing?

More related errors