C++获取文件的有关信息

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一 获取文件的大小

1 代码

#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>

int main() {
    struct stat buf;
    stat("/etc/hosts", &buf);
    printf("/etc/hosts file size = %d\n", buf.st_size);
    
    stat("test.cpp", &buf);
    printf("test.cpp size = %d\n", buf.st_size);
}

2 运行

[root@localhost test]# g++ test.cpp -o test
[root@localhost test]# ./test
/etc/hosts file size = 158
test.cpp size = 258
[root@localhost test]# ll test.cpp
-rw-r--r--. 1 root root 258 Mar 24 15:32 test.cpp
[root@localhost test]# ll /etc/hosts
-rw-r--r--. 1 root root 158 Jun  7  2013 /etc/hosts

二 判断文件是否存在

1 代码

#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>//for ENOENT
#include <string.h>//for memset
int main()
{
    struct stat st;
    memset(&st, 0, sizeof(st));
    if (!stat("test.cpp", &st)) //如果myfil.txt不存在，stat就会返回非０
    {
        if (st.st_size >= 0) //加了一层保证
        {
            printf("test.cpp exists.\n");
        }
    }
    else     if(ENOENT == errno)
        printf("test.cpp does NOT exist:%d\n",errno);
}

2 运行

[root@localhost test]# g++ test.cpp -o test
[root@localhost test]# ./test
test.cpp exists.