下面是一个简单的词法分析器
#include <stdio.h>#include <string.h>using namespace std ;int main(){char str[150] ;//freopen("C:\\Users\\Lionel\\Desktop\\1.txt","r",stdin) ;int row = 1 , cow = 0 ;while(gets(str)){char temp[10] ;int index = 0 , i = 0;while(i<strlen(str)+1){if(str[i] == ' ' || str[i] == '\t' || str[i] == '\0'){temp[index] = '\0' ;if(!strcmp(temp,"if")){printf("IF(%d,%d)\n",row,i-index+1) ;}else{bool flag = false ;for(int j = 0 ; j < index ; ++j){if(temp[j]<'0' || temp[j]>'9'){flag = true ;break ;}}if(flag){printf("ID(%s)(%d,%d)\n",temp,row,i-index+1) ;}else{printf("NUM(%s)(%d,%d)\n",temp,row,i-index+1) ;}}while((str[i] == ' ' || str[i] == '\t') && (str[i+1] == ' ' || str[i+1] == '\t')){++i ;}index = 0 ;}else{temp[index++] = str[i] ;}++i ;}row++ ;}return 0 ;}与君共勉
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有希望在的地方，痛苦也成欢乐
