编译原理识别保留字和标识符的自动机

/* * 该自动机能够判断输入的字符串是关键字(保留字)，还是标示符，或者不是标示符 * 这个自动机还不能识别数字 * 关键字用一个二维数组给出，标示符的命名规则是：由数字、下划线和字母组成，数字不能开头，最多只有8个字符，超过八个时前8个有效。 * iszm函数的作用是判断一个字符是否为字母 * sign表示标示符，blz表示保留字 */ #include "stdio.h" #include "string.h" int iszm(char n); int isblz(char s[]); main() { int i=0; char ch,c[9],temp; printf("Please input the string :"); temp=getchar(); c[i++]=temp; while((ch=getchar())!='\n') { if(iszm(ch)==0 && ch!='_' && (ch>'9' || ch<'0')) break; if(i<8) //当标示符的字符个数超过8个时，只有前8个有效 c[i++]=ch; } c[i]='\0'; if(iszm(temp)==0 && temp!='_') printf("The string you entered isn't a sign or a blz,you can't define a sign like this.\n"); else if(ch!='\n') printf("The string you entered isn't a right sign!\n"); else if (isblz(c)==1) printf("The string you entered is a blz, It's %s\n",c); else if (isblz(c)==0) printf("The string you entered is a right sign,It's %s\n",c); } int iszm(char n) { if((n>='A' && n<='Z') || (n>='a' && n<='z')) return 1; //是字母 else return 0; //不是字母 } int isblz(char s[]) { char blz[32][9]={"auto","break","case","char","const","continue","default","do","double","else","enum","extern","float","for","goto","if","int","long","register","return","short","signed","sizeof","static","struct","switch","typedef","unsigned","union","void","volatile","while"}; int i=0; for(i=0;i<32;i++) { if(strcmp(s,blz[i])==0) break; } if(i==32) return 0; //不是保留字 else return 1; //是保留字 }