setjump 和 longjump

大家好，欢迎来到IT知识分享网。

#include "apue.h" #include <setjmp.h> #define TOK_ADD 5 jmp_buf jmpbuffer; int main(void) { char line[MAXLINE]; if (setjmp(jmpbuffer) != 0) printf("error"); while (fgets(line, MAXLINE, stdin) != NULL) do_line(line); exit(0); } ... void cmd_add(void) { int token; token = get_token(); if (token < 0) /* an error has occurred */ longjmp(jmpbuffer, 1); /* rest of processing for this command */ } 

#include "apue.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) { 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); }

 $ cc testjmp.c compile without any optimization $ ./a.out in f1(): globval = 95, autoval = 96, regival = 97, volaval = 98, statval = 99 after longjmp: globval = 95, autoval = 96, regival = 97, volaval = 98, statval = 99 $ cc -O testjmp.c compile with full optimization $ ./a.out in f1(): globval = 95, autoval = 96, regival = 97, volaval = 98, statval = 99 after longjmp: globval = 95, autoval = 2, regival = 3, volaval = 98, statval = 99