C++ Primer(第五版)学习笔记_5_标准模板库string(2)

标签：c++   leetcode   

#include <iostream>
#include <stdio.h>
#include <string>

using namespace std;

int main(int argc, char* argv[])
{
    string s;
    s = "cat dog cat";
    //查找第一个字符'c',返回下标值
    cout << s.find('c') << endl;
    //查找第一个子串"c",返回下标值
    cout << s.find("c") << endl;
    //查找第一个子串"cat",返回下标值
    cout << s.find("cat") << endl;
    //查找第一个子串"dog",返回下标值
    cout << s.find("dog") << endl;
    //查找第一个子串"pig",查不到则返回4294967295
    cout << s.find("pig") << endl;
    if(s.find("pig") == string::npos)
        cout << "没有找到" << endl;
    return 0;
}

#include <iostream>
#include <stdio.h>
#include <string>

using namespace std;

int main(int argc, char* argv[])
{
    string s;
    s = "cat dog cat";
    //使用比较符号">","<","=="
    cout << (s == "cat dog cat") << endl;
    //s比"abc"字符串大，返回1
    cout << s.compare("abc") << endl;
    //异常：s比"cat dog c"字符串大，返回2，发现返回值是剩下2个值不一致则返回2.
    cout << s.compare("cat dog c") << endl;
    //s比"dog"小，返回-1
    cout << s.compare("dog") << endl;
    //s与"cat dog cat"相等，返回0
    cout << s.compare("cat dog cat") << endl;

    return 0;
}

#include <iostream>
#include <string>
#include <algorithm>

using namespace std;

int main(int argc, char* argv[])
{
    string s;
    s = "123456789";
    reverse(s.begin(), s.end());
    cout << s << endl;
    return 0;
}

#include <iostream>
#include <string>
#include <algorithm>

using namespace std;

int main(int argc, char* argv[])
{
    vector<string> str;
    str.push_back("Jack");
    str.push_back("Mike");
    str.push_back("Tom");
    for(int i = 0; i < str.size(); i++)
        cout << str[i] << endl;
    cout << str[0][0] << endl;
    cout << str[1][0] << endl;
    cout << str[2].size() << endl;
    return 0;
}

#include <iostream>
#include <string>

using namespace std;

int main(int argc, char* argv[])
{
    string s;
    s = "1234059";
    int sum = 0;
    for(int i = 0; i < s.length(); i++)
    {
        if(s[i] == '0')
            sum += 0;
        else if(s[i] == '1')
            sum += 1;
        else if(s[i] == '2')
            sum += 2;
        else if(s[i] == '3')
            sum += 3;
        else if(s[i] == '4')
            sum += 4;
        else if(s[i] == '5')
            sum += 5;
        else if(s[i] == '6')
            sum += 6;
        else if(s[i] == '7')
            sum += 7;
        else if(s[i] == '8')
            sum += 8;
        else if(s[i] == '9')
            sum += 9;
    }
    cout << sum << endl;
    return 0;
}

#include <iostream>
#include <stdio.h>
#include <string>

using namespace std;

int main(int argc, char* argv[])
{
    string s;
    char ss[100];
    //输入字符串到字符数组中
    scanf("%s", &ss);
    //字符数组赋值字符串对象
    s = ss;
    //用pringf输出字符串对象，要采用c_str()方法
    printf(s.c_str());
    cout << endl;
    //用printf输出字符数组
    printf("%s", ss);
    cout << endl;
    return 0;
}

#include <iostream>
#include <stdio.h>
#include <string>

using namespace std;

int main(int argc, char* argv[])
{
    string s1, s2, s3;
    char sa[100], sb[100], sc[100];
    //将字符串分离成数字，分隔符为空格
    sscanf("abc 123 pc", "%s %s %s", sa, sb, sc);
    s1 = sa;
    s2 = sb;
    s3 = sc;
    cout << s1 << " " << s2 << " " << s3 << endl;
    //将字符串分离成数字，分隔符为空格
    //当用到数字的时候，跟scanf一样，它需要传指针地址
    int a, b, c;
    sscanf("1 2 3", "%d %d %d", &a, &b, &c);
    cout << a << " " << b << " " << c << endl;
    //当字符串分离成数字，分隔符为","和"$"
    //当用到数字的时候，跟scanf一样，它要传指针地址
    int x, y, z;
    sscanf("4,5$6", "%d,%d$%d", &x, &y, &z);
    cout << x << " " << y << " " << z << endl;
    return 0;
}

#include <iostream>
#include <sstream>
#include <string>
#include <stdio.h>

using namespace std;

//将数值转化为string的第二种方法：C++方法
string convertToString(double x)
{
    ostringstream o;
    if(o << x)
        return o.str();
    return "error";
}

double convertFromString(const string &s)
{
    istringstream i(s);
    double x;
    if(i >> x)
        return x;
    return 0.0;
}

int main(int argc, char* argv[])
{
    //将数值转化为string的第一种方法：C方法
    char b[10];
    string a;
    sprintf(b, "%d", 1975);
    a = b;
    cout << a << endl;

    //将数值转化为string的第二种方法：C++方法
    string cc = convertToString(1976);
    cout << cc << endl;

    //将string转化为数值的第一种方法：C++方法
    string dd = "2006";
    int p = convertFromString(dd) + 2;
    cout << p << endl;
    return 0;
}

C++ Primer(第五版)学习笔记_5_标准模板库string(2)

标签：c++   leetcode   

原文地址：http://blog.csdn.net/keyyuanxin/article/details/46831185