# V3007. Odd semicolon ';' after 'if/for/while' operator.

The analyzer has detected a potential error when a semicolon ';' is used after statement 'for', 'while', or 'if'.

Consider the following example:

    int i = 0;
    ....
    for(i = 0; i < arr.Count(); ++i);
      arr[i] = i;

In this code, the programmer wanted the assignment operation to process all of the array's items but added a semicolon by mistake after the closing parenthesis of the loop. It results in the assignment operation being executed only once. Moreover, it also causes an array index out of bounds error.

The correct version of the code should look as follows:

    int i = 0;
    ....
    for(i = 0; i < arr.Count(); ++i)
      arr[i] = i;

The presence of a semicolon ';' after said statements does not always indicate an error, of course. Sometimes a loop body is not required to execute the needed statements, and the use of a semicolon is justified in such code. For example:

    int i;
    for (i = 0; !char.IsWhiteSpace(str[i]); ++i) ;
    Console.WriteLine(i);

The analyzer won't output a warning in this and some other cases.

This diagnostic is classified as:

CWE-691