Unix环境高级编程(7-6 longjmp对各类变量的影响)

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本文深入探讨了C语言中setjmp和longjmp函数的使用，展示如何在程序中实现异常处理和跳转，通过实例展示了它们在控制流程中的强大能力。

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

static void f1(int, int, int, int);
static void f2(void);
static jmp_buf jmpbuffer;
static int globval;

int main(void)
{
        int             autoval;
        register int    regival;
        volatile int    volaval;
        static int      statval;

        globval = 1; autoval = 2; regival = 3; volaval = 4; statval = 5;

        if(setjmp(jmpbuffer)!=0) /*  此处setjmp的返回值0，通过调用longjmp返回值改变为1(通过gdb调试得出的结果)  */
        {
                printf("after longjmp:\n");
                printf("globval=%d,autoval=%d,regival=%d,volaval=%d,statval=%d\n",globval,autoval,regival,volaval,statval);
                exit(0);
        }
        /*
         *Change variables after setjmp,but before longjmp.
         */
        globval = 95; autoval = 96; regival = 97; volaval = 98; statval = 99;

        f1(autoval,regival,volaval,statval); /*  never returns  */
        exit(0);
}

static void f1(int i,int j,int k, int l)
{
        printf("in f1():\n");
        printf("globval=%d,autoval=%d,regival=%d,volaval=%d,statval=%d\n",globval,i,j,k,l);
        f2();
}

static void f2(void)
{
        longjmp(jmpbuffer,1);
}