4. 利用标准I/O操作中的fopen、fread、fwrite、fseek、fclose等函数实现文件显示命令cat

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

int main(int argc, char *argv[]) {
FILE *fp;
char ch;

if (argc != 2) {
printf("Usage: %s filename\n", argv[0]);
exit(EXIT_FAILURE);
}

fp = fopen(argv[1], "r");

if (fp == NULL) {
printf("Error: cannot open file %s\n", argv[1]);
exit(EXIT_FAILURE);
}

while ((ch = fgetc(fp)) != EOF) {
putchar(ch);
}

fclose(fp);
return 0;
}

相关问题

4. 利用标准I/O操作中的fopen、fread、fwrite、fseek、fclose等函数实现文件显示命令cat和cp的功能。

1. cat命令实现：

#include <iostream>
#include <cstdio>

int main(int argc, char* argv[]) {
    FILE* fp;
    char buffer[1024];

    if (argc < 2) {
        std::cout << "Usage: cat <filename>" << std::endl;
        return 1;
    }

    fp = fopen(argv[1], "r");
    if (fp == nullptr) {
        std::cout << "Error opening file" << std::endl;
        return 1;
    }

    while (fgets(buffer, 1024, fp)) {
        std::cout << buffer;
    }

    fclose(fp);

    return 0;
}

2. cp命令实现：

#include <cstdio>

int main(int argc, char* argv[]) {
    FILE* source;
    FILE* destination;
    char buffer[1024];
    size_t count;

    if (argc < 3) {
        printf("Usage: cp <source> <destination>\n");
        return 1;
    }

    source = fopen(argv[1], "rb");
    if (source == nullptr) {
        printf("Error opening source file\n");
        return 1;
    }

    destination = fopen(argv[2], "wb");
    if (destination == nullptr) {
        printf("Error opening destination file\n");
        fclose(source);
        return 1;
    }

    while ((count = fread(buffer, 1, 1024, source))) {
        fwrite(buffer, 1, count, destination);
    }

    fclose(source);
    fclose(destination);

    return 0;
}

. 利用标准I/O操作中的fopen、fread、fwrite、fseek、fclose等函数实现文件显示命令cat和 文件复制cp的功能。

1. 文件显示命令cat的实现：

#include <stdio.h>

int main(int argc, char *argv[]) {
    if (argc != 2) {
        printf("Usage: %s <filename>\n", argv[0]);
        return 1;
    }
    FILE *fp = fopen(argv[1], "r");
    if (fp == NULL) {
        printf("Error opening file %s\n", argv[1]);
        return 1;
    }
    char buffer[BUFSIZ];
    size_t nread;
    while ((nread = fread(buffer, 1, BUFSIZ, fp)) > 0) {
        fwrite(buffer, 1, nread, stdout);
    }
    fclose(fp);
    return 0;
}

2. 文件复制命令cp的实现：

#include <stdio.h>

int main(int argc, char *argv[]) {
    if (argc != 3) {
        printf("Usage: %s <source> <destination>\n", argv[0]);
        return 1;
    }
    FILE *src = fopen(argv[1], "rb");
    if (src == NULL) {
        printf("Error opening source file %s\n", argv[1]);
        return 1;
    }
    FILE *dst = fopen(argv[2], "wb");
    if (dst == NULL) {
        printf("Error opening destination file %s\n", argv[2]);
        fclose(src);
        return 1;
    }
    char buffer[BUFSIZ];
    size_t nread;
    while ((nread = fread(buffer, 1, BUFSIZ, src)) > 0) {
        fwrite(buffer, 1, nread, dst);
    }
    fclose(src);
    fclose(dst);
    return 0;
}