initializing variable in different-different position in windows is giving error - c++

Question

I am initializing simple int variable in my code but it gives some unwanted errors... If I use integer(or other data type) variable in some places it gives error. I write down my code and put comment where integer variable is showing error.
#include<stdio.h>
#include<Windows.h>
//int i; ///********* no problem ************
int main()
{
//int i; ///********* no problem ************
STARTUPINFO si;
PROCESS_INFORMATION pi;
//int i; ///********* no problem ************
ZeroMemory(&si,sizeof(si));
//int i; // error C2143: syntax error : missing ';' before 'type'
si.cb=sizeof(si);
//int i; //error C2143: syntax error : missing ';' before 'type'
ZeroMemory(&pi,sizeof(pi));
//int i; //error C2143: syntax error : missing ';' before 'type'
if(CreateProcess("C:\\Windows\\System32\\notepad.exe",NULL,NULL,NULL,FALSE,NORMAL_PRIORITY_CLASS,NULL,NULL,&si,&pi))
{
//int i; ///********* no problem ************
printf("process created\n pid is=%d tid is=%d\n",pi.dwProcessId,pi.dwThreadId);
}
else
{
//int i; ///********* no problem ************
printf("process creation error\n");
}
// int i; // error C2143: syntax error : missing ';' before 'type'
}
I am using cl.exe compiler and visual studio 2012.I am compiling code from command line
cl process.c

Answer 1

The Visual Studio compiler doesn't support C99, which you are attempting to use.
You must use just C90, i.e. keep your variable declarations at the top of their containing scope.

Answer 2

You must declare all your variables just after the { of a function.
This is because Visual Studio supports C89 and C89 forbids mixed declarations. In C99 and later,variables can be declared anywhere