for (int i = 0; i < len / 2; i++) { temp = str[i]; str[i] = str[len - 1 - i]; str[len - 1 - i] = temp;具体解读这几行代码

这几行代码是一个字符串反转的操作，利用一个 for 循环，将字符串的前半部分与后半部分中对应位置的字符进行交换，从而实现字符串反转的效果。其中 len 为字符串的长度，temp 为临时变量，用于存储交换时的一个字符。

相关问题

#include <stdio.h> #include <string.h> void reverse(char *str) { int len = strlen(str); for (int i = 0; i < len/2; i++) { char temp = str[i]; str[i] = str[len - i - 1]; str[len - i - 1] = temp; } } int main() { char str[] = "Hello World!"; printf("Original String: %s\n", str); reverse(str); printf("Reversed String: %s\n", str); return 0; }纠错

这段代码的实现是将一个字符串进行翻转，并输出翻转后的结果。代码中出现了一个小错误，应该在开头添加一个换行符，即将第一行改为：

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

同时，建议在输出翻转后的字符串时，也加上一个换行符，以便更好地显示输出结果。修改后的代码如下：

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

void reverse(char *str) {
    int len = strlen(str);
    for (int i = 0; i < len/2; i++) {
        char temp = str[i];
        str[i] = str[len - i - 1];
        str[len - i - 1] = temp;
    }
}

int main() {
    char str[] = "Hello World!";
    printf("Original String: %s\n", str);
    reverse(str);
    printf("Reversed String: %s\n\n", str);
    return 0;
}

用python语言翻译如下代码://线性移位寄存器生成密钥 int IFSR(int K) { int feature = 143; int temp1, temp2; temp1 = feature & K; while (temp1) { temp2 = (temp2 + temp1 & 1) % 2; temp1 = temp1 >> 1; } K = ((K << 1) & 255) + temp2; return K; } //生成16轮密钥 void getKeys(int round) { for (int i = 0; i < round; i++) { int temp = 0; for (int j = 0; j < 8; j++) { K = IFSR(K); temp += K & 1; temp = temp << 1; } temp = temp >> 1; Keys[i] = temp; } } //轮函数 int F(int RE, int Ki) { Ki = Ki >> 4; int temp = Ki ^ RE; return temp; } //明文加密 void encrypy(int round) { int m, temp1, temp_j; int le, re; m = strlen(str_plaincode); for (int i = 0; i < m; i++) { int temp1; if (i == 0) temp1 = IV; else temp1 = ((IV << j) ^ temp_j) & 255; le = temp1 >> 4; re = temp1 & 15; for (int j = 0; j < round; j++) { int temp2 = le; le = re; re = (temp2 ^ F(re, Keys[j])); } temp_j = (re << 4) + le; temp_j = temp_j >> (8 - j); str_ciphertext[i] = str_plaincode[i] ^ temp_j; } } //解密

以下是Python代码的翻译：

# 线性移位寄存器生成密钥
def IFSR(K):
    feature = 143
    temp1, temp2 = 0, 0
    temp1 = feature & K
    while temp1:
        temp2 = (temp2 + temp1 & 1) % 2
        temp1 >>= 1
    K = ((K << 1) & 255) + temp2
    return K

# 生成16轮密钥
def getKeys(round):
    global Keys
    Keys = [0] * round
    for i in range(round):
        temp = 0
        for j in range(8):
            global K
            K = IFSR(K)
            temp += K & 1
            temp <<= 1
        temp >>= 1
        Keys[i] = temp

# 轮函数
def F(RE, Ki):
    Ki = Ki >> 4
    temp = Ki ^ RE
    return temp

# 明文加密
def encrypy(round):
    global str_ciphertext
    m = len(str_plaincode)
    for i in range(m):
        temp1 = 0
        if i == 0:
            temp1 = IV
        else:
            temp1 = ((IV << j) ^ temp_j) & 255
        le = temp1 >> 4
        re = temp1 & 15
        for j in range(round):
            temp2 = le
            le = re
            re = (temp2 ^ F(re, Keys[j]))
        temp_j = (re << 4) + le
        temp_j = temp_j >> (8 - j)
        str_ciphertext.append(str_plaincode[i] ^ temp_j)

# 解密
def decode():
    global test
    m = len(str_ciphertext)
    for i in range(m):
        temp1 = 0
        if i == 0:
            temp1 = IV
        else:
            temp1 = ((IV << j) ^ temp_j) & 255
        le = temp1 >> 4
        re = temp1 & 15
        for j in range(round):
            temp2 = le
            le = re
            re = (temp2 ^ F(re, Keys[round-j-1]))
        temp_j = (re << 4) + le
        temp_j = temp_j >> (8 - j)
        test += chr(str_ciphertext[i] ^ temp_j)