简单读取同名.txt或命令行指定文件内容并输出

#include <stdio.h>
#include <string.h>

int main(int argc, char *argv[]) {
    FILE *file;
    char filename[256];

    if (argc > 1) {
        strncpy(filename, argv[1], sizeof(filename));
    } else {
		strncpy(filename, argv[0], sizeof(filename));
        strcat(filename, ".txt");
    }

    file = fopen(filename, "r");
    if (file == NULL) {
        printf("Failed to open file %s\n", filename);
        return 1;
    }

    char line[256];
    while (fgets(line, sizeof(line), file)) {
        printf("%s", line);
    }

    fclose(file);
    return 0;
}