Question

我似乎无法获得阵列的长度或向后打印！请帮忙？！
void GetStringLenght和Print Backwards底部的函数不起作用

#include <iostream>

void ReadString(char* c, int maxLength);

void GetStringLength(char* c, int* length);

void PrintString(char* const c);

void PrintStringBackwards(char* const c);

int main()
{
    const int SIZE = 50;
    char ca[SIZE];
    char* pc = ca;
    int fPrints = 0;
    int bPrints = 0;
    int lengthChecks = 0;

    char selection = 'z';
    while (selection != 'Q') {
        std::cout << "\n[ 1] Test ReadString\n";
        std::cout << "[ 2] Test GetStringLength\n";
        std::cout << "[ 3] Test PrintString\n";
        std::cout << "[ 4] Test PrintStringBackwards\n";
        std::cout << "[Q] Quit\n";
        std::cout << "Selection: ";
        std::cin >> selection;
        std::cin.ignore();
        std::cout << std::endl;

        switch (selection) {
        //Test ReadString
        case '1':
            ReadString(pc, SIZE);
            break;
        //Test GetStringLength
        case '2': {
            lengthChecks += 1;
            int length = 0;
            GetStringLength(pc, &length);
            std::cout << "Length[" << lengthChecks << "]=" << length << std::endl;
            break;
        }
        //Test PrintString
        case '3':
            fPrints += 1;
            std::cout << "Foward[" << fPrints << "]=";
            PrintString(pc);
            std::cout << std::endl;
            break;
        //[ 4] Test PrintStringBackwards
        case '4':
            bPrints += 1;
            std::cout << "Backwards[" << bPrints << "]=";
            PrintStringBackwards(pc);
            std::cout << std::endl;
            break;

        case 'Q':
            break;
        default:
            break;
        } //end switch

    } //end while
    std::cout << "Press ENTER";
    std::cin.get();
    return 0;
}

void ReadString(char* c, int maxLength)
{
    std::cout << "Enter a string less than " << maxLength << " characters." << std::endl;

    std::cin.getline(c, maxLength, '\n');
}

//BELOW THIS DOESNT WORK EITHER///
//////////////////////////////////////////
void GetStringLength(char* c, int* length)
{
    for (int i = 0; i < *length; i++) {
        if (c[i] == '\0')
            *length = i - 1;
    }
}

void PrintString(char* const c)
{
    int counter = 0;
    for (int i = 0; i < 100; i++) {
        if (c[i] == '\0') {
            counter = i;
            break;
        } //end if
    } //end for
    for (int j = 0; j < counter; j++) {
        std::cout << c[j];
        if (j == counter)
            std::cout << '\0';
    } //end for
    std::cout << std::endl;
} //end void

void PrintStringBackwards(char* const c)
{
    //this is where I’m lost! I’ve tried 25 different ways and everything is error.
}

Answer 1

要获得C字符串（char*）的长度，您可以使用strlen(...)。要向后打印，请执行以下操作：

for(int i = strlen(str) - 1; i >= 0; --i)
    std::cout << str[i];

Answer 2

考虑for (int i = 0; i < *length; i++)，其中i和*length都是0，就像你的情况一样......那个循环会执行吗？不...考虑一个循环，当x为0时，return x;设置为str[x]和'\0'。即strlen中的循环就是这样做的。

对于向后打印，从最高索引开始（由strlen或您的函数返回一次）并递减直到达到0，然后在这些偏移处打印字符。

顺便提一下，strlen中提供了{p> <cstring>，而不仅仅是<string> ...因为它是强制函数，所以它始终是任何C ++实现的一部分。您应该只使用strlen ...

Easy C ++ =数组长度和反向WITHOUT <string>

2 个答案: