程序设计方法学简易计算器

1、实验1简易计算器：第一步：程序基本架构：#include <iostream>#include <fstream>#include <string>using namespace std;#define maxlength 1024bool fail = false;数据结构：操作数栈struct stack_cchar datamaxlength;int top; od;操作符栈struct stack_ddouble datamaxlengthl;int top; op;int main()ifstream infile;ofstream outfile

2、;string expr;infile.open("infile.txtn);outfile.open(ncalc.logn);if (infile.fail()outfile « ”无法读取表达式！ ” « endl;elsewhile (!infile.eof()infile » expr;calc(expr);outfile « endl « endl;infile.close(); outfile.close();return 0;第二步：对calc (expr)进行精细主程序void calc(string s) bool

3、b = check(s); if(b=false)cout « "表达式不合法"« endl; else mycalc(s);计算void mycalc(string s)表达式合法性检查bool check(string s)第三步：对 check(),mycalc()函数精细bool check(string s) if(bool check _bars(s) return false;if(bool check_all_letters(s) return false;return true;bool check _bars(string s)boo

4、l check_all_letters(string s) void mycalc(string expr) op.top = od.top = 0;int now = 0;double tmp = 0, weg;bool point = false;fail = false;while (now < expr.length()if (now = 0)od.data+od.top =开始读入表达式时,将压入符号栈中switch (exprnow)/m读入的表达式中的字符进彳亍分枝操作 一case : opl(exprnow);/遇到时，进行 opl 操作break;case *('

5、;: op2(exprnow); /遇到'('时，进行 op2 操作break;case : op3(exprfnow); 遇到'+'吋，进彳亍 op3 操作break;case : op4(exprnow); 遇至时，进行 op4 操作break;case' 1 case 2case 3case 4case 5case 6case 7case !8'case 9op5(exprnow); 遇到数字时,进彳亍op5操作 break;case y:op6(exprnow); 遇到了吋，进彳亍op6操作 break;case 7:point = tr

6、ue;/遇到t吋开启小数模式 weg = 0.1;break;now+;if (fail)break;void opl(exprnow)void op2(exprnow)void op3(exprnow)void op4(exprnow)void op5(exprnow)void op6(exprnow)第四步:对 check_bars(),check_all_letters(),opl(),op2(),op3(),op4(),op5(),op6()函 数精细bool check_alletters(string e)for (int i = 0; i < e.length(); i+)

7、操作数if (ei >= 48) && (ei <= 57) continue;if (efi = t) continue;运算符if (ei = 4)continue; if (ei = '-*) continue;讦(efi ='*') continue;if (ei = 7)continue;界限符讦(ei = continue; if (ei = *(*) continue;if (ei = 7) continue;return false; return true;bool check_bars(string e)int r=0,1

8、=0;for (int i = 0; i < eength(); i+) 讦(ei = *)') r+4-;else if (efi = '(') 1+;if (r != 1)outfilevv”发现不匹配的括号，请检查您的表达式：” vvevvendl; outfilevv” 中止计算！” « endl;return false;return true;void opl(exprnow)if ( now = expr.length。-1)while (od.dataod.top !=if (od.top <= 0) ii (op.top <

9、= 0) fail_op_od(); op.dataop.top-l=mycalc(op.dataop.top-l,od.dataod.top, op.dataop.top);od.top-；op.top-;if (fail) break;讦(op.top != 1) ii (od.top != 1) fail_op_od();讦(fail) break;expr.erase(exp r.length()-l, 1);outfile « expr « "=outfile « op.dataop.top « endl;else fail = tr

10、ue;void op2(exprnow)od.data+od.top = exprnow;void op3(exprnow)if (getpid(od.dataod.top) >=getpid(exprnow) && (getpid(od.dataod.top) <3)讦(od.top <= 0) ii (op.top <= 0) fail_op_od();op.dataop.top-ll = mycalc(op.dataf op.top-11, od.datafod.top, op.dataop.top);op.top;od.top;讦(fail) b

11、reak;od.data+od.top = exprnow;void op4(exprnow)od.data+od.top = exprnow;void op5(exprnow)if (!point)tmp = tmp*10 + (exprnow-48);tmp += weg * (exprnow-48);weg /= 10;if (exprnow+l = t)now+;continue;if (exprnow+l < 48) ii (exprnow+l > 57)point = false;op.data+op.top = tmp;tmp = 0;if (getpid(od.da

12、taod.top)>getpid(od.dataod. top-1 )&&(od.dataod.top != '(*)if (od.top <= 0) ii (op.top <= 0) fail_op_od();op.datafop.top 1= mycalc(op.dataop.topl,od.dataf od.top, op.dataop.top);op.top;od.top-;if (fail) break;void op6(exprfnow)while (od.dataod.top) != '(*)讦(od.top <= 0) i

13、i (op.top <= 0) fail_op_od();op.dataop.top-l = mycalc(op.dataop.top-1, od.dataod.top,op.datafop.top);op.top;od.top;if (fail) break;if (od.datafod.top = *(') od.top;else fail_op_od();第四步：对 void fail_op_od(), int getpid(char tmp)进彳亍精细 void fail_op_od()if (fail) return;outfile « ”发现无效的运算操作，可能您的操作数与操作符不相匹配” vv endl;outfile « "屮止计算！ “vvendl;fail = true; int getpid(char tmp)if (tmp = '+') return 1; if (tmp = '-*) return 1;if (tmp = '*) return 2; if (tmp = 7') return 2;if (tmp = '(') return 3;return 100;实