C语言实现命题逻辑计算器：生成真值表并判断公式类型

#include <stdio.h> #include <stdlib.h>

// 定义逻辑联结词的枚举类型 typedef enum { AND, OR, NOT, IMPLIES, EQUIVALENT } Connective;

// 定义命题变元的结构体 typedef struct { int value; int isAssigned; } PropositionVariable;

// 定义命题公式的结构体 typedef struct { Connective connective; struct Proposition* left; struct Proposition* right; } Proposition;

// 初始化命题变元 void initPropositionVariable(PropositionVariable* pv) { pv->value = 0; pv->isAssigned = 0; }

// 获取命题变元的值 int getPropositionVariableValue(PropositionVariable* pv) { if (pv->isAssigned) { return pv->value; } else { printf("命题变元未赋值！\n"); exit(1); } }

// 初始化命题公式 void initProposition(Proposition* prop) { prop->left = NULL; prop->right = NULL; }

// 释放命题公式的内存 void freeProposition(Proposition* prop) { if (prop != NULL) { freeProposition(prop->left); freeProposition(prop->right); free(prop); } }

// 获取命题公式的结果 int getPropositionResult(Proposition* prop, PropositionVariable* p, PropositionVariable* q, PropositionVariable* r) { if (prop == NULL) { printf("命题公式为空！\n"); exit(1); }

switch (prop->connective) {
    case AND:
        return getPropositionResult(prop->left, p, q, r) && getPropositionResult(prop->right, p, q, r);
    case OR:
        return getPropositionResult(prop->left, p, q, r) || getPropositionResult(prop->right, p, q, r);
    case NOT:
        return !getPropositionResult(prop->left, p, q, r);
    case IMPLIES:
        return !getPropositionResult(prop->left, p, q, r) || getPropositionResult(prop->right, p, q, r);
    case EQUIVALENT:
        return getPropositionResult(prop->left, p, q, r) == getPropositionResult(prop->right, p, q, r);
    default:
        printf("无效的逻辑联结词！\n");
        exit(1);
}

}

// 输出真值表 void printTruthTable(Proposition* prop, PropositionVariable* p, PropositionVariable* q, PropositionVariable* r) { int i, j, k; printf("P\tQ\tR\t结果\n"); for (i = 0; i < 2; i++) { p->value = i; for (j = 0; j < 2; j++) { q->value = j; for (k = 0; k < 2; k++) { r->value = k; printf("%d\t%d\t%d\t%d\n", p->value, q->value, r->value, getPropositionResult(prop, p, q, r)); } } } }

// 判断命题公式类型 void determinePropositionType(Proposition* prop, PropositionVariable* p, PropositionVariable* q, PropositionVariable* r) { int isTautology = 1; // 永真式 int isContradiction = 1; // 不可满足式

int i, j, k;
for (i = 0; i < 2; i++) {
    p->value = i;
    for (j = 0; j < 2; j++) {
        q->value = j;
        for (k = 0; k < 2; k++) {
            r->value = k;
            int result = getPropositionResult(prop, p, q, r);
            if (result == 0) {
                isTautology = 0;
            } else {
                isContradiction = 0;
            }
        }
    }
}

if (isTautology) {
    printf("命题公式为永真式。\n");
} else if (isContradiction) {
    printf("命题公式为不可满足式。\n");
} else {
    printf("命题公式为可满足式。\n");
}

}

// 获取逻辑联结词 Connective getConnective() { int choice; printf("请选择逻辑联结词：\n"); printf("1. 与(AND)\n"); printf("2. 或(OR)\n"); printf("3. 非(NOT)\n"); printf("4. 蕴含(IMPLIES)\n"); printf("5. 等价(EQUIVALENT)\n"); scanf("%d", &choice);

switch (choice) {
    case 1:
        return AND;
    case 2:
        return OR;
    case 3:
        return NOT;
    case 4:
        return IMPLIES;
    case 5:
        return EQUIVALENT;
    default:
        printf("无效的选择！\n");
        exit(1);
}

}

// 创建命题公式 Proposition* createProposition(PropositionVariable* p, PropositionVariable* q, PropositionVariable* r) { Proposition* prop = (Proposition*) malloc(sizeof(Proposition)); prop->connective = getConnective();

if (prop->connective == NOT) {
    prop->left = createProposition(p, q, r);
    prop->right = NULL;
} else {
    prop->left = createProposition(p, q, r);
    prop->right = createProposition(p, q, r);
}

return prop;

}

int main() { PropositionVariable p, q, r; initPropositionVariable(&p); initPropositionVariable(&q); initPropositionVariable(&r);

int choice;
do {
    printf("请输入命题公式：\n");
    Proposition* prop = createProposition(&p, &q, &r);
    printf("真值表：\n");
    printTruthTable(prop, &p, &q, &r);
    determinePropositionType(prop, &p, &q, &r);

    freeProposition(prop);

    printf("是否继续输入命题公式？(1-是，0-否)：");
    scanf("%d", &choice);
} while (choice == 1);

return 0;

}