what's an expression and expression statement in c++?

Question

I\'ve read that usually statements in c++ end with a semi-colon; so that might help explain what an expression statement would be. But then what would you call an expression

Answer 1

These are expressions (remember math?):

1
6 * 7
a + b * 3
sin(3) + 7
a > b
a ? 1 : 0
func()
mystring + gimmeAString() + std::string("\n")

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The following are all statements:

int x;                            // Also a declaration.
x = 0;                            // Also an assignment.
if(expr) { /*...*/ }              // This is why it's called an "if-statement".
for(expr; expr; expr) { /*...*/ } // For-loop.

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A statement is usually made up of an expression:

if(a > b)           // a > b is an expr.
    while(true)     // true is an expr.
        func();     // func() is an expr.