关键字是预定义或保留的单词,在C ++库中可用,具有固定的含义,并且用于执行内部操作。C ++语言支持64个以上的关键字。
每个关键字都以小写字母形式存在,例如auto,break,case,const,continue,int等。
C ++语言中的32个关键字,也可用C语言提供。
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30个不在C中但已添加到C ++中的保留字
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
关键字是保留字,不能在程序中用作变量名。
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,则字符串为关键字)
#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); }
输出结果
which is a keyword