linux下getcwd头文件

char *getcwd(char *buf, size_t size);

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

int main() {
    char cwd[PATH_MAX];
    if (getcwd(cwd, sizeof(cwd)) != NULL) {
        printf("Current working directory: %s\n", cwd);
    } else {
        perror("getcwd() error");
        return 1;
    }
    return 0;
}

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

int main() {
    char *ptr = NULL;
    size_t size = 0;
    while (1) {
        if (getcwd(ptr, size) == NULL) {
            if (errno == ERANGE) {
                size *= 2;
                ptr = realloc(ptr, size);
                if (ptr == NULL) {
                    perror("realloc");
                    return 1;
                }
            } else {
                perror("getcwd");
                free(ptr);
                return 1;
            }
        } else {
            printf("Current working directory: %s\n", ptr);
            free(ptr);
            break;
        }
    }
    return 0;
}