编写自定义函数： 1.关于运算符栈和操作数栈的初始化、进栈、出栈、取栈顶元素 2.根据运算符“+、−、*、/”返回相应操作数的结果 3.输入表达式并得到相应计算值 C语言编写

在C语言中，编写一个简单的四则运算计算器涉及到操作符栈和操作数栈的管理，我们可以创建两个栈结构体，一个用于存储操作数，另一个用于存储运算符。这里是一个基本的示例：

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

typedef struct Stack {
    int top;
    int capacity;
    double items[100];
} Stack;

Stack *create_stack(int size) {
    Stack *stack = (Stack*)malloc(sizeof(Stack));
    stack->top = -1;
    stack->capacity = size;
    return stack;
}

void push(Stack *stack, double item) {
    if (stack->top >= stack->capacity - 1) {
        printf("Stack overflow\n");
        return;
    }
    stack->items[++stack->top] = item;
}

double pop(Stack *stack) {
    if (stack->top == -1) {
        printf("Stack underflow\n");
        return 0;
    }
    return stack->items[stack->top--];
}

bool is_empty(Stack *stack) {
    return stack-1;
}

double calculate_value(Stack *operators, Stack *operands, char op) {
    double operand2, result;
    switch(op) {
        case '+':
            operand2 = pop(operands);
            result = pop(operands) + operand2;
            push(operands, result);
            break;
        case '-':
            operand2 = pop(operands);
            result = pop(operands) - operand2;
            push(operands, result);
            break;
        case '*':
            operand2 = pop(operands);
            result = pop(operands) * operand2;
            push(operands, result);
            break;
        case '/':
            if (pop(operands) != 0) {
                operand2 = pop(operands);
                result = pop(operands) / operand2;
                push(operands, result);
            } else {
                printf("Division by zero error\n");
                return 0;
            }
            break;
        default:
            printf("Invalid operator\n");
            return 0;
    }
    return result;
}

int main() {
    Stack *operands = create_stack(10);
    Stack *operators = create_stack(10);

    // 用户输入操作数和运算符
    while (!is_empty(operands)) {
        char input[50];
        scanf("%s", input);
        if (*input == '+' || *input == '-' || *input == '*' || *input == '/') {
            double num = atof(input); // 转换字符串到浮点数
            push(operands, num);
        } else {
            double op = calculate_value(operators, operands, input[0]);
            if (op != 0) {
                push(operators, op);
            } else {
                // 处理错误情况
            }
        }
        getchar(); // 消耗掉回车符
    }

    // 输出结果
    if (!is_empty(operands)) {
        printf("Final result: %.2f\n", pop(operands));
    } else {
        printf("No valid expression provided.\n");
    }

    // 清理栈
    while (!is_empty(operands)) {
        pop(operands);
    }
    while (!is_empty(operators)) {
        pop(operators);
    }

    free(operands);
    free(operators);
    return 0;
}

这个程序会读取用户输入的一串四则运算表达式，逐个处理其中的操作数和运算符，并按照栈的原则计算最终结果。注意，此代码仅作为示例，实际应用中需要更完善的错误处理和用户交互界面。