2025年C++编程中遇到的问题总结

科技前沿 • 2025-02-18 08:35 • 阅读 58

大家好，我是讯享网，很高兴认识大家。

1，字符串的末尾是’\0’，不是’/0’，否者下列程序运行时会字符串越界

 int i = 0; while (str[i] != '\0') { 
    i++; }

讯享网

2题目是牛客网上剑指offer的第二题

题目描述
请实现一个函数，将一个字符串中的每个空格替换成“%20”。例如，当字符串为We Are Happy.则经过替换之后的字符串为We%20Are%20Happy。
代码

讯享网class Solution { 
    public: void replaceSpace(char *str,int length) { 
    } };

可以正确运行的代码

讯享网

#include <iostream> #include <vector> #include <string> using namespace std; void main() { 
    const int a = 100; //string str = "we are happy"; char str[a] = "we are happy"; //string str1; int i = 0; int j = 0; int length = 0; int space_num = 0; while (str[i] != '\0') { 
    length++; if (str[i] == ' ') { 
    space_num++; } i++; } int len = length + space_num * 2; while (length >= 0) { 
    if (str[length] == ' ') { 
    str[len--] = '0'; str[len--] = '2'; str[len--] = '%'; } else { 
    str[len--] = str[length]; //len--; } length--; } cout << str << endl; system("pause"); }

错误的代码

讯享网#include <iostream> #include <vector> #include <string> using namespace std; void main() { 
    const int a = 100; string str = "we are happy"; //char str[a] = "ABC CBA I LOVE YOU!"; //char str[a] = "we are happy"; //string str1; int i = 0; int j = 0; int length = 0; int space_num = 0; while (str[i] != '\0') { 
    length++; if (str[i] == ' ') { 
    space_num++; } i++; } int len = length + space_num * 2; while (length >= 0) { 
    if (str[length] == ' ') { 
    str[len--] = '0'; str[len--] = '2'; str[len--] = '%'; } else { 
    str[len--] = str[length]; //len--; } length--; } cout << str << endl; system("pause"); }

错误原因
因为操作的是字符串不是字符

class Solution { 
    public: void replaceSpace(char *str,int length) { 
    } };

C++中的string类型结尾没有’\0’,而char数组的结尾都是：’\0’,所以char类型数组的长度为看的长度+1，最后一个字符为’\0’

讯享网#include<iostream> using namespace std; int main() { 
    char ch[]="7"; int a=sizeof(ch); cout<<a<<"\t"<<ch[0]<<"A"<<ch[1]<<"A"<<endl; string str="a"; cout<<str.size()<<endl; cout<<str[0]<<endl; return 0; }

上述的结果

2 7AA 1 a

2025年C++编程中遇到的问题总结

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