C library functions - signal ()
C standard library - <signal.h>
description
C library functionvoid (* signal (int sig, void (* func) (int))) (int) to set up a function to process the signal with a signal handler that is sigparameters.
statement
The following is a statement signal () function.
void (*signal(int sig, void (*func)(int)))(int)
parameter
- sig - signal codes in the signal processing used in the program as a variable.Here are some important criteria signal constants:
| 宏 | 信号 |
|---|---|
| SIGABRT | (Signal Abort) 程序异常终止。 |
| SIGFPE | (Signal Floating-Point Exception) 算术运算出错，如除数为 0 或溢出（不一定是浮点运算）。 |
| SIGILL | (Signal Illegal Instruction) 非法函数映象，如非法指令，通常是由于代码中的某个变体或者尝试执行数据导致的。 |
| SIGINT | (Signal Interrupt) 中断信号，如 ctrl-C，通常由用户生成。 |
| SIGSEGV | (Signal Segmentation Violation) 非法访问存储器，如访问不存在的内存单元。 |
| SIGTERM | (Signal Terminate) 发送给本程序的终止请求信号。 |
- func - a pointer to a function.It can be a function defined by the program, it can be one of the predefined function below:
| SIG_DFL | 默认的信号处理程序。 |
| SIG_IGN | 忽视信号。 |
return value
This function returns the value of the signal handler before the return SIG_ERR when an error occurs.
Examples
The following example illustrates the signal () function is used.
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
void sighandler(int);
int main()
{
signal(SIGINT, sighandler);
while(1)
{
printf("开始休眠一秒钟...\n");
sleep(1);
}
return(0);
}
void sighandler(int signum)
{
printf("捕获信号 %d，跳出...\n", signum);
exit(1);
}
Let's compile and run the above program, which will produce the following results, and the program will enter an infinite loop, use the CTRL + C keys out of the program.
开始休眠一秒钟... 开始休眠一秒钟... 开始休眠一秒钟... 开始休眠一秒钟... 开始休眠一秒钟... 捕获信号 2，跳出...