“语法错误：缺少';' 在带有预编译标头的c ++项目中，在“ {””之前

Question

When trying to compile simple c++ project, I get the following error:

syntax error : missing ';' before '{'

I did my research. Compiler doesn't allow declaration of variables inside of a for loop, which is very inconvenient for me. If I declare loop variables before the for loop, the error disappears.

This is a c++ project with "stdafx.h" precompiled header.

Is this compiler behavior (C89) enforced by the fact that I'm using precompiled header or did I scr**ed something up with my config in the past ? Is there any way of circumventing this befavior ?

PS I'm using visual studio 2012 on windows 7 64-bit;

Code samples:

1. error is on the first line

    for (int idx = 0, int i = 100; idx < (sizeof(anTestScores) / sizeof(int)); i++, idx++) { anTestScores[idx] = i; } 

2. this compiles

    int idx; int i; for (idx = 0, i = 100; idx < (sizeof(anTestScores) / sizeof(int)); i++, idx++) { anTestScores[idx] = i; } 

Answer 1

Go with

for (int idx = 0, i = 100; idx < (sizeof(anTestScores) / sizeof(int)); i++, idx++) { anTestScores[idx] = i; }

This declares two variables of type int in the first statement of the for loop.

The reason this works and your other attempt doesn't is as follows:

Each declaration statement has to be separated from each other by a ; , but the same ; is used to separate parts of the for(;;) loop's header so you tried to get around it by using the ',' operator. Which didn't work due to syntax error