如何拆分等式的字符串

Question

我是新来的，如有错误请见谅。

我需要一个将字符串拆分为字符的程序。我的意思是如果用户写 "Hello"; 那个程序应该使它成为 "a[]={'H','e','l','l','o'}" 或类似的东西。用 C++ 真的可以吗？我要用它来计算方程式。如果你有更好的想法（没有ax^2+bx+c），请告诉我。谢谢你的帮助。祝你有个愉快的一天。

Answer 1

从字符串中提取字符并将它们存储到字符数组中

简单方法（使用字符串索引）：

#include<iostream>

using namespace std;
// Using the namespace std to use string.

int main(int argc, char** argv) {
    string input;
    cout << "Enter a string: ";
    cin>>input;     // To read the input from the user.
    
    int strLength = input.length(); // To compute the length of the string.
    char * charArray = new char[strLength]; //Dynamic memory allocation

    /**
     * The following for loop converts the string into an array.
    */
    for (int i=0; i<strLength; i++) {
        charArray[i] = input[i];
    }

    cout << endl << "The elements of the character array are as follows: {";
    for (int i = 0; i < strLength; i++) {
        if (i != strLength - 1) {
            cout << "\'" << charArray[i] << "\', ";
        } else {
            cout << "\'" << charArray[i] << "\'}";
        }   
    }

    delete [] charArray;
    return 0;
}

示例输出：

Enter a string: Hello

The elements of the character array are as follows: {'H', 'e', 'l', 'l', 'o'}
RUN SUCCESSFUL (total time: 3s)

要处理更复杂的输入，或者如果您对更复杂的结构感兴趣，以下程序应该对您有所帮助：

#include<iostream>

using namespace std;
// Using the namespace std to use string.

int main(int argc, char** argv) {
    string input;
    cout << "Enter a string: ";
    cin>>input;     // To read the input from the user.
    
    int strLength = input.length(); // To compute the length of the string.
    char * charArray = new char[strLength]; //Dynamic memory allocation
    int loopVar = 0;

    /**
     * The following for loop converts the string into an array.
    */
    for (const char* iterativeVar = input.c_str(); *iterativeVar; iterativeVar++) {
        charArray[loopVar] = *iterativeVar;
        ++loopVar;
    }

    cout << endl << "The elements of the character array are as follows: {";
    for (int i = 0; i < strLength; i++) {
        if (i != strLength - 1) {
            cout << "\'" << charArray[i] << "\', ";
        } else {
            cout << "\'" << charArray[i] << "\'}";
        }   
    }

    delete [] charArray;
    return 0;
}

示例输出：

Enter a string: Hello

The elements of the character array are as follows: {'H', 'e', 'l', 'l', 'o'}
RUN SUCCESSFUL (total time: 2s)

记得在for循环中使用const char *。否则会报错如下：

newmain.cpp: In function 'int main(int, char**)':
newmain.cpp:23:42: error: invalid conversion from 'const char*' to 'char*' [-fpermissive]
     for (char* iterativeVar = input.c_str(); *iterativeVar; iterativeVar++) {

不要忘记使用 delete 释放内存，该内存使用 new 运算符分配给字符数组，如下所示：

delete [] charArray;

否则，您的程序可能会遇到内存泄漏。

从字符串中提取整数字符并将它们存储到整数数组中：

以下程序应该对您有所帮助：

#include<iostream>

using namespace std;
// Using the namespace std to use string.

int main(int argc, char** argv) {
    string input;
    cout << "Enter a number: ";
    cin>>input;     // To read the input from the user.
    
    int strLength = input.length(); // To compute the length of the string.
    int * intArray = new int[strLength]; //Dynamic memory allocation
    int loopVar = 0;

    /**
     * The following for loop converts the string into an array.
    */
    for (const char* iterativeVar = input.c_str(); *iterativeVar; iterativeVar++) {
        intArray[loopVar] = (*iterativeVar-'0');
        ++loopVar;
    }

    cout << endl << "The elements of the integer array are as follows: {";
    for (int i = 0; i < strLength; i++) {
        if (i != strLength - 1) {
            cout << intArray[i] << ", ";
        } else {
            cout <<intArray[i]<<"}";
        }   
    }

    delete [] intArray;
    return 0;
}

示例输出：

Enter a number: 123456789

The elements of the integer array are as follows: {1, 2, 3, 4, 5, 6, 7, 8, 9}
RUN SUCCESSFUL (total time: 4s)

如何拆分等式的字符串

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从字符串中提取字符并将它们存储到字符数组中

从字符串中提取整数字符并将它们存储到整数数组中：