发布时间 : 2024/5/2 11:27:21 星期四 文章利用真值表法求取主析取范式以及主合取范式的实现更新完毕开始阅读4b59f353a26925c52dc5bf11

else Clear(); }

void Calculator::Change() //将输入的字符串转化为可计算的表达式 { int k = 0, t = 0; int flag = 1; //标记，防止相同的命题变元赋入不同的值 int count = 0; for (int i = 0; i < pow(2,count); i++) { k=1; for (int m = 0; m < length; m++) { if (isalpha(str[m])) //将原来的命题变元修改为真值 { if (flag == 1) { if(tv[k] == 0) expression[m] = '0'; else expression[m] = '1'; k++; } else expression[m] = '0'; flag = 1; for (t = m; t >= 0; t--) if ((str[m+1] == str[t]) && isalpha(str[m+1]) && isalpha(str[t])) flag = 0; } else { expression[m] = str[m]; //逻辑联结词不变 for (t = m; t >= 0; t--) if ((str[m+1] == str[t]) && isalpha(str[m+1]) && isalpha(str[t])) flag = 0; } } for (int t = 0; t < length; t++) for (int j = t; j < length; j++) if (str[t] == str[j]) expression[j] = expression[t]; //相同的命题变元复制赋值 }

}

int Calculator::Run() { SeqStack s1; //联结词栈 char ch, y; char p[100]; int i = 0; s1.Push('#'); for (int temp=0; temp < length ; temp++) { ch = expression[temp]; if (isdigit(ch)) { p[i++] = ch; } else if(ch == ')') for(s1.Top(y), s1.Pop(); y != '('; s1.Top(y), s1.Pop()) p[i++] = y; else { if(ch == '!') p[i++] = '1'; //非运算，在!前加1，将!视作双目操作符 for(s1.Top(y), s1.Pop(); icp(ch) <= isp(y); s1.Top(y), s1.Pop()) p[i++] = y; s1.Push(y); s1.Push(ch); } } while(!s1.IsEmpty()) { s1.Top(y); s1.Pop(); if(y != '#') p[i++] = y; } p[i++] = '#';

/* ------↑中缀表达式转化为后缀表达式----- ------↓计算后缀表达式结果------------- */ bool newop; for (i = 0; p[i] !='#'; i++) { switch(p[i]) { case '!':

case '&': case '|': case '>': DoOperator(p[i]); break; default: cin.putback(p[i]); cin >> newop; PushOperand(newop); break; } } if (s.Top(newop)) { cout << (int)newop << endl; return (int)newop; //输出并返回最终结果 } }

void Calculator::Solve() { cout << \标语 cout << \ 欢迎进入逻辑运算软件 **\ cout << \ (可运算真值表，主范式，支持括号) **\ cout << \ **\ cout << \ 用!表示not 用&表示and **\ cout << \ 用|表示or 用>表示蕴含 **\ cout << \ **\ cout << \ cout << \请输入合法的命题公式(以#结尾): \ int flag = 1; //标记，防止重复添加命题变元 int count = 0; //命题变元的数目 cin >> str; //输入命题公式 length = strlen(str) - 1; char index[10]; //命题变元数组 for (int i = 0; i < length; i++) //逐次添加命题变元 { if (isalpha(str[i]) && (flag == 1)) index[count++] = str[i]; flag=1; for (int k = 0; k < count; k++) if (index[k] == str[i+1]) flag=0; } if (!count) {

cout << \无命题变元,重新输入!\ system(\ system(\ Solve(); }

cout << \真值表:\for (int w = 0; w < count; w++) cout << index[w] << ' '; for (w = 0; w < length; w++) cout << str[w]; cout << endl;

int *truth = new int[pow(2,count)]; int xx = 0, dx = 0; //小项，大项

for (int r = 0; r < pow(2,count); r++) //输出真值表 { for (int j = 1; j <= count; j++) cout << tv[j] << ' '; Change();

truth[r] = Run(); if (truth[r]) //记录小项和大项的个数 xx++; else dx++; Plus(tv,count); }

if(xx > 1) //输出主析取范式 { int flag_xx = 0; cout << \主析取范式为 \ for(r = 0; r < pow(2,count); r++) { if (truth[r]) { if (flag_xx) cout << \ cout << \ flag_xx = 1; } } cout << endl; } else cout << \没有主析取范式!\if(dx > 1) //输出主合取范式 {

int flag_dx = 0; cout << \主合取范式为 \ for(r = 0; r < pow(2,count); r++) { if (!truth[r]) { if (flag_dx) cout << \ cout << \ flag_dx = 1; } } cout << endl; } else cout << \没有主合取范式!\ cout << \是否继续运算?(Y/N)\ char goon; cin >> goon; if (goon=='y' || goon=='Y') { system(\ Solve(); //递归调用Solve，重新计算 } else exit(0); }

int main() { Calculator Cal(100); Cal.Solve(); return 0; }