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#include<stdlib.h>
#include<math.h>
#include<stdio.h>
int i=3;
void f(){
++i;
printf("%d\n",i);
}
int main(){
double d=cos(0.0);
printf("%f\n",d);
return 0;
}
它打印"1.000000",如预期。如果我在gdb命令行调用函数:
(gdb) b main
Breakpoint 1 at 0x40055b: file x.c, line 10.
(gdb) r
Starting program: /home/x/a.out
Breakpoint 1, main () at x.c:10
10 ++i;
(gdb) call f()
4
(gdb) call f() # ok
5
(gdb) call cos(0.0)
No symbol "cos" in current context. # 为什么找不到?
(gdb) call printf("%d\n",i) # ok
5
$1 = 2
(gdb) call putchar('a')
$2 = 97