1:命名空间
2:C与C++字符串的区别和基本操作
3:枚举类型
命名空间
#include <string> #include <ctype.h> #include <vector> #include <iostream> #include <fstream> // using declarations states our intent to use these names from the namespace std using namespace std; namespace one{ string name = "namesapce one的name"; } namespace two{ string name = "namesapce two的name"; } string name = "全局的name"; int main() {
//using one::name;//不行,同一范围内重定义,与下面的name有冲突 cout << one::name << endl; cout << two::name << endl; string name = "局部name"; cout << name << endl; cout << ::name << endl; //全局没有范围。没有放在名字空间中的东西都成为放在匿名名字空间, //匿名就是没有名字,直接用双冒号表示,表示全局的或者外面的 /* system("pause");*/ return 0; }
c风格字符串和c++的区别
#include <string> #include <ctype.h> #include <vector> #include <iostream> #include <fstream> // using declarations states our intent to use these names from the namespace std using namespace std; void printString(char *s1, char *s2); int main() { char cs1[30] = "i am cool"; //最多存29个字符,最后一个必须为结尾符,如果定义为csa[9]会出错,没把结尾符算进去 char cs2[30] = "you are cool"; printString(cs1, cs2); strcpy(cs2, cs1); printString(cs1, cs2); cout << "cs1与cs2比较后的结果,返回值为0,-1,1"<<strcmp(cs1, cs2)<< endl; cout << "cs2的长度为(不包括结尾符) "<<strlen(cs2) << endl; cout << "将cs1的附加到cs1后面"<<strcat(cs1, cs2) << endl; cout << cs1 << endl; return 0; } void printString(char *s1,char *s2) { cout << "s1= "<<s1 << " s2= "<< s2 << endl; }
#include <string> #include <ctype.h> #include <vector> #include <iostream> #include <fstream> // using declarations states our intent to use these names from the namespace std using namespace std; void printString(string s1, string s2); int main() { string cpps1 = "i am cool"; string cpps2 = "you are cool";
string::size_type index= cpps1.find("i");//查找第一个字符出现的位置
cout << index << endl;
const char*s1 = cpps1.c_str();// c++风格转换为c风格 printString(cpps1, cpps2); cpps1 = cpps2; printString(cpps1, cpps2); /* cout << "cs1与cs2比较后的结果,返回值为0,-1,1"<<strcmp(cs1, cs2)<< endl;*/ cout << "cs2的长度为(不包括结尾符) "<<cpps2.size() << endl; cout << "将cs1的附加到cs1后面"<< cpps1+cpps2<< endl; cout << cpps1 << endl; cout << "将cs1的附加到cs1后面" << (cpps1+=cpps2) << endl; cout << cpps1 << endl; return 0; } void printString(string s1,string s2) { cout << "s1= "<<s1 << " s2= "<< s2 << endl; }
两种字符串混合使用时,会自动转成c++风格
枚举类型
#include <string> #include <ctype.h> #include <vector> #include <iostream> #include <fstream> // using declarations states our intent to use these names from the namespace std using namespace std; enum Color{BLACK,WHITE,GREEN,YELLOW,RED}; enum Color_me{ BLACK_me, WHITE_me, GREEN_me, YELLOW_me, RED_me }; int main() { int v; Color c; //c里面的数字虽然看上去像整型,但是是Color型,比整型的范围要小 Color_me c2; c = BLACK; cout << c << endl; //输出0 v = c; //将范围小的BLACK复制到Int类型是可行的 cout << v << endl; //c = v; //将int类型变为BLACK类型不可行,缩小了范围。 //c2 = c; //两个不同的枚举类型之间的值得类型也是不同的,不可以相互赋值 return 0; }
c++名字空间,C与C++字符串的区别,枚举类型,布布扣,bubuko.com
原文:http://www.cnblogs.com/yican/p/3915019.html