c++ - gettimeofday() 未在此范围内声明 - Cygwin

Question

cygwin 可以使用 gettimeofday() 吗？我收到错误:

lab8.cpp: In function ‘int main()’:
lab8.cpp:62:30: error: ‘gettimeofday’ was not declared in this scope
     gettimeofday(&start, NULL);
                              ^
makefile:14: recipe for target 'lab8.o' failed
make: *** [lab8.o] Error 1

我肯定包括了<sys/time.h> .是否有我必须安装的软件包，或者它不能在 Windows 上运行？

编辑:这是一个产生相同错误的简单测试:

#include <sys/time.h>

int main() {
    struct timeval start;

    gettimeofday(&start, NULL);
}

出现错误:

$ g++ -c -Wall -g -std=c++11 test.cpp -o test.o
test.cpp: In function ‘int main()’:
test.cpp:6:30: error: ‘gettimeofday’ was not declared in this scope
     gettimeofday(&start, NULL);

Answer 1

您需要定义 _BSD_SOURCE 以包含声明 gettimeofday(根据下面的链接从 glibc2.2.2 开始)

#define _BSD_SOURCE

#include <sys/time.h>

int main() {
    struct timeval start;

    gettimeofday(&start, NULL);
}

gettimeofday() - Unix, Linux System Call