使用stat来检测文件是否存在(慢？)

#include<stdio.h>
#include <unistd.h>

int main() {
    if (access("file.txt", F_OK) == 0) {
        printf("File exists.\n");
    } else {
        printf("File does not exist.\n");
    }
    return 0;
}

#include<stdio.h>
#include <fcntl.h>
#include <unistd.h>

int main() {
    int fd = open("file.txt", O_RDONLY);
    if (fd != -1) {
        printf("File exists.\n");
        close(fd);
    } else {
        printf("File does not exist.\n");
    }
    return 0;
}