c++ - 有符号/无符号不匹配和函数在转换为函数时不带 2 个参数

Question

所以我能够编写一个将字符串转换为摩尔斯电码的程序，但是老师想要一个函数中的转换部分，我做到了，但是它给出了错误警告 C4018:“<”:第 29 行有符号/无符号不匹配和错误 C2660:“toMorse”:函数在第 18 行不接受 2 个参数你会认为在能够让正常程序运行之后这将是小菜一碟，但此时我的大脑已经死了。任何帮助找出它为什么这样做的帮助将不胜感激，尽管我想我可以在 main{} 中将它全部交上任务不会太糟糕。

#include <iostream>
#include <string>
using namespace std;

// Function Prototypes
string toMorse(char);

int main()
{

    string userInput;

    cout << "Please input a string to convert to morse code." << endl;
    getline(cin, userInput, '\n');

    int stringSize = userInput.length();

    toMorse(userInput, stringSize);

}

//*****************************************************************
//Function to convert into morse code
//*****************************************************************
string toMorse(string morseArray, int stringSize)
{
    string *toConvert = new string[stringSize];

    for (size_t i = 0; i < stringSize; i += 1)
    {
        if (toupper(userInput.at(i)) == 'A')
        toConvert[i] = ".-";
    // will fill in the rest once problems are solved
        else toConvert[i] = " ";
    }

    for (size_t x = 0; x < stringSize; x += 1)
        cout << toConvert[x] << "  ";

    cout << endl;

    delete[] toConvert;

    return 0;
}

所以我能够根据给出的提示让它工作，但现在每次我运行以下代码时(它翻译正确，就在我按下回车键时它显示正确的输入但也说“调试断言失败!表达式: MSVCP120D.dll 第 1168 行上的空指针无效

#include <iostream>
#include <string>
using namespace std;

// Function Prototypes
string toMorse(string, size_t);

int main()
{

    string userInput;

    cout << "Please input a string to convert to morse code." << endl;
    getline(cin, userInput, '\n');

    int stringSize = userInput.length();

    toMorse(userInput, stringSize);

}

//*****************************************************************
//Function to convert into morse code
//*****************************************************************
string toMorse(string morseArray, size_t stringSize)
{
    string *toConvert = new string[stringSize];

    for (size_t i = 0; i < stringSize; i += 1)
    {
        if (toupper(morseArray.at(i)) == ' ')
            toConvert[i] = " ";
        else if (toupper(morseArray.at(i)) == ',')
            toConvert[i] = "--..--";
        else if (toupper(morseArray.at(i)) == '.')
            toConvert[i] = ".-.-.-";
        else if (toupper(morseArray.at(i)) == '?')
            toConvert[i] = "..--..";
        else if (morseArray.at(i) == '0')
            toConvert[i] = "-----";
        else if (morseArray.at(i) == '1')
            toConvert[i] = ".----";
        else if (morseArray.at(i) == '2')
            toConvert[i] = "..---";
        else if (morseArray.at(i) == '3')
            toConvert[i] = "...--";
        else if (morseArray.at(i) == '4')
            toConvert[i] = "....-";
        else if (morseArray.at(i) == '5')
            toConvert[i] = ".....";
        else if (morseArray.at(i) == '6')
            toConvert[i] = "-....";
        else if (morseArray.at(i) == '7')
            toConvert[i] = "--...";
        else if (morseArray.at(i) == '8')
            toConvert[i] = "---..";
        else if (morseArray.at(i) == '9')
            toConvert[i] = "----.";
        else if (toupper(morseArray.at(i)) == 'A')
            toConvert[i] = ".-";
        else if (toupper(morseArray.at(i)) == 'B')
            toConvert[i] = "-...";
        else if (toupper(morseArray.at(i)) == 'C')
            toConvert[i] = "-.-.";
        else if (toupper(morseArray.at(i)) == 'D')
            toConvert[i] = "-..";
        else if (toupper(morseArray.at(i)) == 'E')
            toConvert[i] = ".";
        else if (toupper(morseArray.at(i)) == 'F')
            toConvert[i] = "..-.";
        else if (toupper(morseArray.at(i)) == 'G')
            toConvert[i] = "--.";
        else if (toupper(morseArray.at(i)) == 'H')
            toConvert[i] = "....";
        else if (toupper(morseArray.at(i)) == 'I')
            toConvert[i] = "..";
        else if (toupper(morseArray.at(i)) == 'J')
            toConvert[i] = ".---";
        else if (toupper(morseArray.at(i)) == 'K')
            toConvert[i] = "-.-";
        else if (toupper(morseArray.at(i)) == 'L')
            toConvert[i] = ".-..";
        else if (toupper(morseArray.at(i)) == 'M')
            toConvert[i] = "--";
        else if (toupper(morseArray.at(i)) == 'N')
            toConvert[i] = "-.";
        else if (toupper(morseArray.at(i)) == 'O')
            toConvert[i] = "---";
        else if (toupper(morseArray.at(i)) == 'P')
            toConvert[i] = ".--.";
        else if (toupper(morseArray.at(i)) == 'Q')
            toConvert[i] = "--.-";
        else if (toupper(morseArray.at(i)) == 'R')
            toConvert[i] = ".-.";
        else if (toupper(morseArray.at(i)) == 'S')
            toConvert[i] = "...";
        else if (toupper(morseArray.at(i)) == 'T')
            toConvert[i] = "-";
        else if (toupper(morseArray.at(i)) == 'U')
            toConvert[i] = "..-";
        else if (toupper(morseArray.at(i)) == 'V')
            toConvert[i] = "...-";
        else if (toupper(morseArray.at(i)) == 'W')
            toConvert[i] = ".--";
        else if (toupper(morseArray.at(i)) == 'X')
            toConvert[i] = "-..-";
        else if (toupper(morseArray.at(i)) == 'Y')
            toConvert[i] = "-.--";
        else if (toupper(morseArray.at(i)) == 'Z')
            toConvert[i] = "--..";
        else toConvert[i] = " ";
    }

    for (size_t x = 0; x < stringSize; x += 1)
        cout << toConvert[x] << "  ";

    cout << endl;

    delete[] toConvert;

    return 0;
}

非常感谢。通过将其更改为正确的返回类型，我能够使其正常运行。再次感谢。感谢大家的帮助!

Answer 1

C4018 警告是关于比较的。您可以像这样使用函数原型(prototype):

string toMorse(string morseArray, size_t stringSize);

此外，您还在文件的开头将 toMorse 函数定义为 string toMorse(char);，这与下面的内容不同。