149 lines
2.4 KiB
C
149 lines
2.4 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include "sqstack.h"
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// !!! 课程不完整，程序未写完
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// TODO: snum和sop需要不同的datatype
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static void compute(sqstack *snum, int *op)
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{
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datatype n1, n2, n;
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st_pop(snum, &n2);
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st_pop(snum, &n1);
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switch (*op)
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{
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case '+': n = n1 + n2; break;
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case '-': n = n1 - n2; break;
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case '*': n = n1 * n2; break;
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case '/': n = n1 / n2; break;
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default: exit(1);
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}
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st_push(snum, &n);
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}
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static deal_bracket(sqstack *snum, sqstack *sop)
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{
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datatype old_op;
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st_top(sop, &old_op);
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while (old_op != '(')
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{
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st_pop(sop, &old_op);
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compute(snum, &old_op);
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st_top(sop, &old_op);
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}
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st_pop(sop, &old_op);
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}
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static int get_pri(int op)
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{
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switch (op)
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{
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case '(': return 0;
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case '+':
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case '-': return 1;
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case '*':
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case '/': return 2;
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}
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}
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static void deal_op(sqstack *snum, sqstack *sop, char op)
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{
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datatype old_op;
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if (st_isempty(sop) || op == '(')
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{
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st_push(sop, &op);
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return;
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}
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st_top(sop, &old_op);
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if (get_pri(op) > get_pri(old_op))
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{
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st_push(sop, &op);
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return;
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}
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while (get_pri(op) <= get_pri(old_op))
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{
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st_pop(sop, &old_op);
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compute(snum, &old_op);
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if (st_isempty(sop))
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break;
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st_top(sop, &old_op);
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}
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st_push(sop, &op);
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}
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int main( )
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{
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int i;
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char str[] = "(11+3)*2-5";
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sqstack *snum, *sop;
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int value = 0;
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int flag = 0;
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int old_op;
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snum = st_create( );
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if (NULL == snum)
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exit(1);
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sop = st_create( );
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if (NULL == sop)
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exit(1);
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while (str[i] != '\n')
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{
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if (str[i] >= '0' && str[i] <= '9')
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{
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value = 10 * value + (str[i] - '0');
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flag = 1;
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}
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else // is a op
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{
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if (flag)
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{
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st_push(snum, &value);
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flag = 0;
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value = 0;
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}
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if (str[i] == ')')
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{
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deal_bracket(snum, sop);
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}
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else // ( + - * /
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{
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deal_op(snum, sop, str[i]);
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}
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}
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i++;
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}
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if (flag)
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st_push(snum, &value);
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while (!st_isempty(sop))
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{
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st_pop(sop, &old_op);
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compute(snum, &old_op);
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}
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st_destroy(snum);
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st_destroy(sop);
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exit(0);
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} |