识别浮点常量问题-编译原理程序实现

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问题

程序实现

源程序

#include <stdio.h>#include <string.h>#include <ctype.h>int getnext(int cur, char c){    switch (cur){        case 1:            if (c=='+' || c=='-') return 2;            if (isdigit(c)) return 3;            return -1;        case 2:            if (isdigit(c)) return 3;            return -1;        case 3:            if (isdigit(c)) return 3;            if (c == '.') return 4;            if (c=='e' || c=='E') return 6;            return -1;        case 4:            if (isdigit(c)) return 5;            return -1;        case 5:            if (isdigit(c)) return 5;            if (c == '\0') return 0;            if (c=='e' || c=='E') return 6;            return -1;        case 6:            if (c=='+' || c=='-') return 7;            if (isdigit(c)) return 8;            return -1;        case 7:            if (isdigit(c)) return 8;            return -1;        case 8:            if (isdigit(c)) return 8;            if (c == '\0') return 0;            return -1;        default:            return -1;    }}int main(){    char s[256];    char t[256];    int i, j, k, len;    int state;    gets(t);    len = strlen(t);    i = 0;    while (i<len && t[i]==' ') i++;    j = len-1;    while (j>=0 && t[j]==' ') j--;    k = 0;    for (; i<=j; i++)        s[k++] = t[i];    s[k] = '\0';    state = 1;    for (i=0; i<=strlen(s); i++){        state = getnext(state, s[i]);        if (state == -1) break;    }    printf("%s\n", state==0 ? "YES" : "NO");    return 0;}

结果

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