The following is an example of possible causes.。

• The file name in Java is not spelled as Main

CORRECT

import java.util.*;
public class Main {// Main
    public static void main(String[] args){
        .
        .
        .
    }
}							

WRONG（ It is spelled as "main." ）

import java.util.*;
public class main {// Not Main
    public static void main(String[] args){
        .
        .
        .
    }
}							

In this case, the following compile message will appear.

Main.java:4: class main is public, should be declared in a file named main.java
public class main {
^
1 error						

The following is a list of common causes.

1. C/C++you have to do return 0; within int-type main function.

CORRECT

#include<stdio.h>
int main()
{
    // Something...
    return 0;
}							

WRONG (Type of main function is void.)

#include<stdio.h>
void main()
{
    // Something...
}							

WRONG (The return value of main function is not 0.)

#include<stdio.h>
#define true 1
int main()
{
    if(true)return 1;
    return 0;
}							

2. Make sure not to contain division by zero.

int res = 2/0;

Please be very careful especially when you are using a variable as a denominator.

for(int i = 0; i < 100; i++){
    res = res + 1/i;
}							

3. Be aware of out-of-range access of array.

int a[10];
printf("%d", a[10]);		

When RE occurs, in some cases you may be able to see the compile message by going to the Results on the top of the screen then show Details on the right side of the screen.