How to correctly use the exit function in C language

How to use the exit function in C language, you need specific code examples

In C language, we often need to terminate the execution of the program early in the program, or in a certain Exit the program under certain conditions. C language provides the exit() function to implement this function. This article will introduce the usage of exit() function and provide corresponding code examples.

The exit() function is a standard library function in C language, which is included in the header file . Its function is to terminate the execution of the program, and can take an integer parameter to specify the status code when the program exits. When a program calls the exit() function, it immediately stops the execution of the program and returns control to the operating system.

The prototype of the exit() function is as follows:

void exit(int status);

Among them, status is the status code when the program exits. As a general rule, a status code of 0 means that the program exited normally, and a status code other than 0 means that the program exited abnormally or an error occurred.

The following is a simple sample code:

#include <stdio.h>
#include <stdlib.h>

int main() {
    int num;
    printf("请输入一个整数：");
    scanf("%d", &num);

    if (num < 0) {
        printf("输入的数小于0，程序异常退出！
");
        exit(1);  // 退出程序，并返回状态码1
    } else {
        printf("输入的数大于等于0，程序正常退出。
");
        exit(0);  // 正常退出，返回状态码0
    }

    return 0;
}

In the above code, first we receive an integer input by the user through the scanf() function. Then, we use if-else statements to judge based on the value entered by the user. If the input number is less than 0, an error message is output, and the exit(1) function is called to exit the program, and status code 1 is returned; if the input number is greater than or equal to 0, a normal exit message is output, and the exit(0) function is called to exit the program. , return status code 0.

It should be noted that the call to the exit() function will immediately terminate the execution of the program, so you need to ensure that the code before the exit() function is called has been completed, such as closing files, releasing memory, etc. In addition, when the exit() function exits the program, it will call various cleanup functions (such as the function registered with atexit()) to ensure the aftermath before the program ends.

In summary, the exit() function is a function in C language that is used to terminate program execution early and return a status code. By calling the exit() function, we can flexibly control the exit of the program in the program and respond to different exceptions. I hope the content of this article can help you better understand and use the exit() function.

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