C 中的 RPN 计算器

Question

有人可以解释一下为什么我在 myString 上使用 strok() 后总是出现乱码吗？我的输出图片在底部。我尝试将 myString 中的每个元素初始化为 NULL 字符，但我的代码仍然不起作用:(

预期输出：

我的输出：

int main()
{
    int i;
    char myString[60];
    char *token;
    float result;
    float x;
    float y;
    struct Stack myStack;
    StackInit(&myStack);


    BOARD_Init();

    printf("\nWelcome to my RPN calculator.\n");
    printf("Enter floats and + - / * in RPN format: \n >");

    for (i = 0; i < sizeof (myString); i++) {
        myString[i] = '[=10=]';
    }

    fgets(myString, sizeof (myString), stdin);



    token = strtok(myString, " ");
    while (token != NULL) {
        printf("%f\n", atof(token));
        token = strtok(NULL, " ");

        if (atof(token) != 0) {
            StackPush(&myStack, atof(token));
        } else if (*token == '+') { // if token is addition
            StackPop(&myStack, &y);
            StackPop(&myStack, &x);
            result = x + y;
            StackPush(&myStack, result);

        } else if (*token == '-') { // if token is subtraction
            StackPop(&myStack, &y);
            StackPop(&myStack, &x);
            result = x - y;
            StackPush(&myStack, result);
        } else if (*token == '*') { // if token is multiplication
            StackPop(&myStack, &y);
            StackPop(&myStack, &x);
            result = x * y;
            StackPush(&myStack, result);
        } else if (*token == '/') { // if token is division
            StackPop(&myStack, &y);
            StackPop(&myStack, &x);
            result = x / y;
            StackPush(&myStack, result);
        }

    }




while (1);

}

Answer 1

正如@BLUEPIXY 在评论中指出的，您的代码在这里有问题：

token = strtok(myString, " ");   // Here you get the first sub string
while (token != NULL) {
    printf("%f\n", atof(token));
    token = strtok(NULL, " ");   // Here you get the second sub string
                                 // and throw away the first substring
                                 // So all the code below is never executed
                                 // for the first substring.
                                 // In other words: You never push the first
                                 // float to the stack

    if (atof(token) != 0) {
        StackPush(&myStack, atof(token));

您应该做的是将 token = strtok(NULL, " "); 移动到循环的末尾：

while (token != NULL) {
    printf("%f\n", atof(token));
    // Not here............. token = strtok(NULL, " ");

    if (atof(token) != 0) {
        StackPush(&myStack, atof(token));
    } else if (*token == '+') { // if token is addition
    //...
    //...
    }

    token = strtok(NULL, " ");    // but here
}

C 中的 RPN 计算器

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