EPI 5.6 STRING AND INTEGER CONVERSIONS

最新推荐文章于 2025-03-26 09:48:37 发布

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本文介绍了一种实现整型到字符串及字符串到整型转换的方法，并通过随机生成的数据进行验证。文中包含两个核心函数：intToString用于将整数转换为字符串；stringToInt则将字符串解析成整数。

#include <iostream>
#include <string>
#include <cassert>
#include <algorithm>
#include <stdexcept>
using namespace std;

string intToString(int x) {
    bool is_negative = false;
    if (x < 0) {
        is_negative = true;
        x = -x;
    }

    string s;
    while (x) {
        s.push_back('0' + x % 10);
        x /= 10;
    }
    if (s.empty()) {
        return "0";
    }
    if (is_negative) {
        s.push_back('-');
    }
    reverse(s.begin(), s.end());
    return s;
}

int stringToInt(const string& s) {
    bool is_negative = (s[0] == '-');
    int x = 0;
    for (int i = is_negative; i < s.size(); i++) {
        if (isdigit(s[i])) {
            x = x * 10 + s[i] - '0';
        } else {
            throw invalid_argument("illegal input");
        }
    }
    return is_negative ? -x : x;
}

string rand_int_string(int len) {
    string ret;
    if (len == 0) {
        return "0";
    }
    if (rand() & 1) {
        ret.push_back('-');
    }
    ret.push_back('1' + rand() % 9);
    while (--len) {
        ret.push_back(rand() % 10 + '0');
    }
    return ret;
}

int main(int argc, char *argv[]) {
    srand(time(nullptr));
    for (int i = 0; i < 10; i++) {
        int x = (rand() & 1 ? -1 : 1) * rand();
        string str = intToString(x);
        cout << x << " " << str << endl;
        assert(x == stoi(str));
        str = rand_int_string(rand() % 10);
        x = stringToInt(str);
        cout << str << " " << x << endl;
        assert(x == stoi(str));
    }
    try {
        stringToInt("123abc");
    } catch (exception &e) {
        cout << e.what() << endl;
    }
    return 0;
}