string_test.cpp

string类的用法的测试

/**********************************************************************************
*                                                                                 *
*  Copyright (c) by Royal. All rights reserved.                                   *
*                                                                                 *
*  Permission to use, copy, modify, and distribute this software for any purpose  *
*  is hereby granted without fee, provided that this copyright and permissions    *
*  notice appear in all copies and derivatives, and that no charge may be made    *
*  for the software and its documentation except to cover cost of distribution.   *
*                                                                                 *
*  This software is provided "as is" without express or implied warranty.         *
*                                                                                 *
**********************************************************************************/

/*
*  Description:
*
*    Examples of std::string.
*
*  History:
*
*    Initial version created by Xyb, May, 2004.
*
*  Notes:
*
*    This code has been written to conform to standard C++ and STL. It has been
*    compiled successfully using GNU C++ 3.2, Borland C++ 5.5, and Visual C++ 7.0.
*/

#include <iostream>
#include <string>

using namespace std;

int main()
{
    // string有12种初始化方式
    cout << endl << "string 有12种初始化方式: " << endl;
    char* chars = "hello the world";
    string s1;
    string s2("hello the world");
    string s3(chars);
    string s4(s2);
    string s5(s2, 6);
    string s6(s2, 6, 3);
    string s7("hello the world", 5); // 注意在参数含义上与s5(s2,5)的区别
    string s8("hello the world", 6, 3);
    string s9(10, 'a');
    string s10(s2.begin() ,s2.end());
    string s11 = s2;
    string s12 = "hello";
    
    cout << "s1: " << s1 << endl;
    cout << "s2: " << s2 << endl;
    cout << "s3: " << s3 << endl;
    cout << "s4: " << s4 << endl;
    cout << "s5: " << s5 << endl;
    cout << "s6: " << s6 << endl;
    cout << "s7: " << s7 << endl;
    cout << "s8: " << s8 << endl;
    cout << "s9: " << s9 << endl;
    cout << "s10: " << s10 << endl;
    cout << "s11: " << s11 << endl;
    cout << "s12: " << s12 << endl;
    

    // size() && length() && capacity() && max_size() && empty()
    cout << endl  << "size() && length() && capacity() && max_size() && empty()" << endl;
    cout << "s2.size(): " << s2.size() << endl;
    cout << "s2.length(): " << s2.length() << endl;
    cout << "s2.max_size(): " << s2.max_size() << endl;
    cout << "s2.capacity(): " << s2.capacity() << endl;
    cout << "s2.empty(): " << (s2.empty() ? "true" : "false") << endl;

    // == && != && < && <= && > && >= 
    cout << endl  << " == && != && < && <= && > && >= " << endl;
    cout << "s2 == s3: " << ((s2 == s3) ? "true" : "false") << endl;
    cout << "chars != s2: " << ((chars != s2) ? "true" : "false") << endl;
    cout << "s2 < s5: " << ((s2 < s5) ? "true" : "false") << endl;
    cout << "s5 > s6: " << ((s5 > s6) ? "true" : "false") << endl;

    // compare()  
    // 0:相等   <0:小于  >0:大于
    cout << endl  << "compare():" << endl;
    cout << "s2.compare(s3): " << s2.compare(s3) << endl;
    cout << "s2.compare(s5): " << s2.compare(s5) << endl;
    cout << "s5.compare(s2): " << s5.compare(s2) << endl;
    cout << "s2.compare(chars):" << s2.compare(chars) << endl;
    cout << "s2.compare(6, 9, s5): " << s2.compare(6, 9, s5) << endl;
    cout << "s2.compare(6, 9, s3, 6, 9): " << s2.compare(6, 9, s3, 6, 9) << endl;
    cout << "s2.compare(6, 9, chars): " << s2.compare(6, 9, chars) << endl;
    cout << "s2.compare(0, 15, chars, 15): " << s2.compare(0, 15, chars, 15) << endl;

    // operator[] && at()
    cout << endl  << "operator[] && at(): " << endl;
    cout << "s2[0]: " << s2[0] << endl;
    cout << "s2[1]: " << s2[1] << endl;
    cout << "s2[14]: " << s2[14] << endl;
    cout << "s2[15]: " << s2[15] << endl;//仅用于测试，s2.at(15)将会导致异常
    cout << "s2.at(10): " << s2.at(10) << endl;

    // c_str() && data() && copy()
    cout << endl  << "c_str() && data() && copy(): " << endl;
    const char* cstr1;
    cstr1 = s2.c_str();
    cout << cstr1 << endl;
    cstr1 = s2.data();
    cout << cstr1 << endl;
    char* cstr2 = new char[s2.size()];
    s2.copy(cstr2, s2.size());
    cout << cstr2 << endl;
    delete[] cstr2;

    // assign() && swap() 
    cout << endl  << "assign() && swap(): " << endl;
    string s14;
    string s15;
    string s16;
    string s17;
    string s18;
    s14.assign(s2);    
    s15.assign(chars);
    s16.assign(s2,6,3);
    s17.assign(chars,10);
    s18.assign(10,'b');
    cout << "s14: " << s14 << endl;
    cout << "s15: " << s15 << endl;
    cout << "s16: " << s16 << endl;
    cout << "s17: " << s17 << endl;
    cout << "s18: " << s18 << endl;
    s14.swap(s16);
    cout << "s14[after s14.swap(s16) ]: " << s14 << endl;
    cout << "s16[after s14.swap(s16) ]: " << s16 << endl;

    // append() && += && push_back()
    cout << endl  << "append() && += && push_back(): " << endl;
    cout << "s2.append(s5): " << s2.append(s5) << endl;
    cout << "s2.append(s2,0,5): " << s2.append(s2,0,5) << endl;
    cout << "s2.append(\"hi\"): " << s2.append(" hi") << endl;
    cout << "s2.append(\"the string\",3): " << s2.append("the string", 3) << endl;
    cout << "s2.append(3, 'c'): " << s2.append(3,'c') << endl;
    cout << "s2.append(s5.begin(), s5.end()): " << s2.append(s5.begin(), s5.end()) << endl;
    cout << "s3 += s5: " << (s3 += s5) <<endl;
    cout << "s3 += \" hihi\": " << (s3 += " hihi") << endl;
    cout << "s3 += \'c\': " << (s3 += 'c') << endl;
    s3.push_back('d');
    cout << "s3[after s3.push_back('d')]: " << s3 << endl;

    // insert()
    cout << endl  << "insert():" << endl;
    cout << "s4.insert(5, s5): " << s4.insert(5,s5) << endl;
    cout << "s4.insert(5, s5, 0, 3): " << s4.insert(5, s5, 0, 3) << endl;
    cout << "s4.insert(5, \"aaa\"): " << s4.insert(5, "aaa") << endl;
    cout << "s4.insert(5, \"how are you\", 3): " << s4.insert(5, "how are you", 3) << endl;
    cout << "s4.insert(5, 3, \'e\'): " << s4.insert(5, 3, 'e') << endl;
    s4.insert(++s4.begin(), 3, 'f');
    cout << "s4[after s4.insert(++s4.begin(), 5, \'f\')]: " << s4 << endl;
    s4.insert(++s4.begin(), 'g');
    cout << "s4[after s4.insert(++s4.begin(),'g')]: " << s4 <<endl ;
    s4.insert(++s4.begin(), s5.begin(), s5.end());
    cout << "s4[after s4.insert(++s4.begin(), s5.begin(), s5.end())]: " << s4 << endl;

    // erase() && resize() && clear()
    cout << endl  << "erase() && resize() && clear(): " << endl;
    s4.erase(30);
    cout << "s4[after s4.erase(30)]: " << s4 << endl;
    s4.erase(20, 5);
    cout << "s4[after s4.erase(20, 5)]: " << s4 << endl;
    s4.erase(s4.begin());
    cout << "s4[after s4.erase(s4.begin())]: " << s4 << endl;
    s4.erase(++s4.begin(), --s4.end());
    cout << "s4[after s4.erase(++s4.begin(), --s4.end())]: " << s4 << endl;
    s4.resize(10);
    cout << "s4[after s4.resize(10)]: " << s4 << endl;
    s4.resize(15, 'h');
    cout << "s4[after s4.resize(15, 'h')]: " << s4 << endl;   
    s4.clear();
    cout << "s4[after s4.clear()]: " << s4 << endl;

    // replace()
    cout << endl  << "replace(): " << endl;
    cout << "s2: " << s2 << endl;
    cout << "s2.replace(5, 10, s5): " << s2.replace(5, 10, s5) << endl;
    cout << "s2.replace(s2.begin(), s2.end(), s5): " << s2.replace(s2.begin(), s2.end(), s5) << endl;
    cout << "s2.replace(0, 3, s5, 4, 5): " << s2.replace(0, 3, s5, 4, 5) << endl; 
    cout << "s2.replace(0, 5, \"hello\", 5): " << s2.replace(0, 5, "hello", 5) << endl;
    cout << "s2.replace(s2.begin(), s2.end(), \"hello\", 5): " << s2.replace(s2.begin(), s2.end(), "hello", 5) << endl;
    cout << "s2.replace(0, 5, 10, \'a\'): " << s2.replace(0, 5, 10, 'a') << endl;
    cout << "s2.replace(s2.begin(), s2.end(), 5, \'b\'): " << s2.replace(s2.begin(), s2.end(), 5, 'b') << endl;
    cout << "s2.replace(s2.begin(), s2.end(), s5.begin(), s5.end()): " << s2.replace(s2.begin(), s2.end(), s5.begin(), s5.end()) << endl; 

    // find() && rfind() 
    // rfind()与find()十分类似，不再举例
    cout << endl  << "find() && rfind(): " << endl;
    string::size_type pos;
    cout << "s3: " << s3 << endl;
    pos = s3.find('e');
    cout << "letter e' position in s3 is: " << pos <<endl; 
    pos = s3.find('e', 10);
    cout << "an e' position in s3 is: " << pos << endl;
    pos = s3.find("the");
    cout << "\"the\" position in s3 is: " << pos << endl;
    pos = s3.find("the", 10);
    cout << "a \"the\" position in s3 is: " << pos << endl;
    pos = s3.find("the", 5);
    cout << "the position in s3 is: " << pos << endl;

    // find_first_of() && find_first_not_of() && find_last_of() && find_last_not_of()
    // find_last与find_first十分类似，不再举例.
    cout << endl  << "find_first_of() && find_first_not_of() && find_last_of() && find_last_not_of(): " << endl;
    s2 = "abcde";
    s3 = "cdefg";
    cout << "s2: " << s2 << endl;
    cout << "s3: " << s3 << endl;
    pos = s2.find_first_of(s3);
    cout << "第一个既在s3中出现也在s2中出现的字母在s2中的位置: " << pos << endl;
    pos = s2.find_first_not_of(s3);
    cout << "第一个未在s3中出现但在s2中出现的字母在s2中的位置: " << pos << endl;

    // substr()
    cout << endl  << "substr(): " << endl;
    cout << "s10: " << s10 << endl;
    cout << "s10.substr(6): " << s10.substr(5) << endl;
    cout << "s10.substr(6, 3): " << s10.substr(6, 3) << endl;

    // +
    cout << endl  << "+ :" << endl;
    s2 = s3 + "tom";
    cout << s2 << endl;
    s2 = s3 + s5;
    cout << s2 << endl;
    s2 = s2 + 'h';
    cout << s2 << endl;

    // 关于 string::npos 常量
    cout << endl  << "关于 npos 常量" << endl;
    cout << "s2: " << s2 << endl;
    string::size_type pos1;// 注意：此处pos1不要用其他类型
    pos1 = s2.find('z');
    if (pos1 != string::npos ) // 一定要使用string::size_type型的变量与string::npos进行比较
    {
        cout << "'z' could find in s2." << endl;        
    }
    else 
    {
        cout << "'z' could not find in s2." << endl;
    }

    return 0;
}