关键字是在C++库中预定义或保留的单词,具有固定的含义,并用于执行内部操作。C++语言支持超过64个关键字。
每个关键字都以小写字母形式存在,如auto、break、case、const、continue、int等。
C++语言中的32个关键字也可在C语言中使用。
auto | double | int | struct |
break | else | long | switch |
case | enum | register | typedef |
char | extern | return | union |
const | float | short | unsigned |
continue | for | signed | void |
default | goto | sizeof | volatile |
do | if | static | while |
这是C++中新增的30个保留字,不在C语言中。
asm | dynamic_cast | namespace | reinterpret_cast |
bool | explicit | new | static_cast |
catch | false | operator | template |
class | friend | private | this |
const_cast | inline | public | throw |
delete | mutable | protected | true |
try | typeid | typename | using |
using | using | wchar_t |
Input: str=”for” Output: for is a keyword
关键字是程序中不能用作变量名的保留字。
C编程语言中有32个关键字。
将字符串与每个关键字进行比较,如果字符串相同,则字符串是关键字。
示例
#include <stdio.h> #include <string.h> int main() { char keyword[32][10]={ "auto","double","int","struct","break","else","long", "switch","case","enum","register","typedef","char", "extern","return","union","const","float","short", "unsigned","continue","for","signed","void","default", "goto","sizeof","voltile","do","if","static","while" } ; char str[]="which"; int flag=0,i; for(i = 0; i < 32; i++) { if(strcmp(str,keyword[i])==0) { flag=1; } } if(flag==1) printf("%s is a keyword",str); else printf("%s is not a keyword",str); }
which is a keyword
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