2月25日C语言习题

#include<iostream>
using std::cout;
using std::endl;
int main()
{
    int recent_page;
    int total_pages = 0;
    const int REST_PAGES = 16023;
    int posible_page = -1;
    // 枚举页数
    int k = -1;
    for (recent_page = 1; k != 0; ++recent_page) {
        total_pages += recent_page;
        if (total_pages - REST_PAGES > 0) {
            k = (total_pages - REST_PAGES - 1) % 2;
            posible_page = (total_pages - REST_PAGES - 1) / 2;
        }
    } 
    cout << "Total page is " << recent_page - 1 << endl;
    cout << "Posible page is " << posible_page << endl;
    return 0;
}

#include<iostream>
using std::cin;
using std::cout;
using std::endl;
#include<cmath>
int main()
{
    int n;    // 浮点数个数
    cin >> n;
    const int MAXLINE = 1000;
    double x[MAXLINE];
    double sum = 0;
    for (int i = 0; i != n; ++i) {
        cin >> x[i];
        sum += x[i];
    }
    // 计算平均值
    double ave = sum / n;
    // 计算标准差
    sum = 0;
    for (int i = 0; i != n; ++i) {
        sum += (x[i] - ave) * (x[i] - ave);
    }
    double vari = sum / n;
    double std = sqrt(vari);
    cout << "Standard Deviation is " << std << endl;
    return 0;
}

#include<iostream>
using std::cout;
using std::cin;
using std::endl;
#include<cstring>
struct WORDS {
    char w[30];
    short w_len;
} word[100];
int process(char *mainstr, struct WORDS *p);
int main()
{
    char str[] = "  Hello world";
    int words = process(str , word);
    cout << "words : " << words << endl;
    for (int i = 0; i != words; ++i) {
        cout << word[i].w << endl;
    }
    return 0;
}

int process(char *mainstr, struct WORDS *p)
{
    int str_index = 0;
    int word_index = 0;
    int words = 0;
    // 跳过开头空格
    while (isspace(*(mainstr + str_index))) {
        ++str_index;
    }
    // 处理单词
    while (str_index < strlen(mainstr) - 1) {
        while (!isspace(*(mainstr + str_index))) {
            (p + words)->w[word_index++] = *(mainstr + str_index);
            ++str_index;
        }
        ++str_index;    // 跳过空格
        // 准备记录下一个单词
        (p + words) -> w[word_index] = ‘\0‘;
        ++words;    
        word_index = 0;
    }
    return words;
}

#include<iostream>
using std::cout;
using std::endl;
// 版本1
int abs(int x)
{
    cout << "Use int abs(int x):" << endl;
    if (x > 0) {
        return x;
    }
    return -x;
}
// 版本2
double abs(double x)
{
    cout << "Use double abs(double x):" << endl;
    if (x > 0) {
        return x;
    }
    return -x;
}
// 函数测试
int main()
{
    cout << abs(-1.7) << endl;
    cout << abs(-1) << endl;
    return 0;
}