字符串与整数互转 手动实现

#include <iostream>
using namespace std;
int main() {
    char str[5] = {'1', '2', '3', '4', '\0'};
    int num = 0;
    int i = 0;
    while(str[i]) {
        num = num * 10 + (str[i++] - '0');  
    }
    cout << num << endl;
    return 0;
}   // 字符串转正整数

#include <iostream>
using namespace std;
int main() {
    // 整数转字符串
    int num = 1234;
    char temp[7], str[7];
    int i = 0, j = 0;
    while(num) {
        // 整数转字符串: +'0' 
        temp[i++] = num % 10 + '0';
        num = num / 10;
    } 
    // 刚刚转化的字符串是逆序的
    while(i >= 0) {
        str[j++] = temp[--i];
    } 
    cout << str << endl;
    return 0;
}