Declarations/definitions as statements in C and C++

Question

I was confused when this wouldn\'t compile in C:

int main()
{
    for (int i = 0; i < 4; ++i)
        int a = 5; // A dependent statement may not be declarati         


        

Answer 1

According to cppreference, C++ includes following types of statements:

1. expression statements;
2. compound statements;
3. selection statements;
4. iteration statements;
5. jump statements;
6. declaration statements;
7. try blocks;
8. atomic and synchronized blocks

While C considers following types of statements:

1. compound statements
2. expression statements
3. selection statements
4. iteration statements
5. jump statements

As you can notice, declarations are not considered statements in C, while it is not this case in C++.

For C++:

int main()
{                                     // start of a compound statement
    int n = 1;                        // declaration statement
    n = n + 1;                        // expression statement
    std::cout << "n = " << n << '\n'; // expression statement
    return 0;                         // return statement
}                                     // end of compound statement

For C:

int main(void)
{                          // start of a compound statement
    int n = 1;             // declaration (not a statement)
    n = n+1;               // expression statement
    printf("n = %d\n", n); // expression statement
    return 0;              // return statement
}                          // end of compound statement