c - 错误: invalid operands to binary < (have 'float *' and 'double' )

Question

我对 C 编程(以及一般情况)是全新的，并且我被困在我的函数的一部分上。我正在尝试进行错误检查，但不断收到错误

error: invalid operands to binary < (have 'float *' and 'double') in line 97 and 100. Does this have to do with the kind of number I am using?

下面粘贴的是我的完整代码

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

// Function Declarations
    void getData      (float* startAmt, float* intRate, int* numYears, int* startYear);

    void calcTaxes    (float  startAmt, float  intRate, int  numYears, int  startYear, float* endAmt, float* intEarned, float* percentGained, int* finalYear);

    void printResults (float  startAmy, float  intRate, int  numYears, int  startYear, float  endAmt, float  intEarned, float  percentGained, int  finalYear);

    int  main (void)
{
  // Local Declarations
      float startAmt;
      float intRate;
      int   numYears;
      int   startYear;
      float endAmt;
      float intEarned;
      float percentGained;
      int   finalYear;

  // Statements
      getData      (&startAmt, &intRate, &numYears, &startYear);
      calcTaxes    ( startAmt,  intRate,  numYears,  startYear,  &endAmt,  &intEarned,  &percentGained,  &finalYear);
      printResults ( startAmt,  intRate,  numYears,  startYear,   endAmt,   intEarned,   percentGained,   finalYear);

      return 0;
}

 //~~~~~~~~~~~~~~~ getData ~~~~~~~~~~~~~~~~~~~~

 /*
  * Function Name:    getData
  *
  * Input Parameters: startAmt, intRate, numYears, startYear
  *
  * Description:      This function reads compound interest data from the keyboard and stores it in the parameters using pointers
  *
  * Return Value:     None
  */

  void getData  (float* startAmt, float* intRate, int* numYears, int* startYear)

{
// Statements
    printf("\nCOP 2220 Project 2: Walter Doherty\n");

    printf("\nEnter a Starting amount (dollars and cents): \n");
    scanf ("%f", startAmt);

    printf("Enter an Interest rate (ex. 2.5 for 2.5%): \n");
    scanf ("%f", intRate);

    printf("Enter the Number of years (integer number): \n");
    scanf ("%d", numYears);

    printf("Enter the Starting year (four digits): \n");
    scanf ("%d", startYear);

// Validations
    if (startAmt < .01)
      exit("Starting amount must be at least one cent.\nExiting");

    if (intRate < .001)
      exit("Interest rate must be at least .1%.\nExiting");

    if (numYears < 1)
      exit("Number of years must be at least 1.\nExiting");

    if (startYear < 999 ^ startYear > 10000)
      exit("Year must be four digits\nExiting");

    return;

}

我还收到有关我的所有 if 的警告消息声明。它说warning: passing argument 1 of 'exit' makes integer from pointer without a cast [enabled by default] 我应该担心这个吗？ Code::Blocks 不会将其记录为错误。 谢谢8)

Answer 1

error: invalid operands to binary < (have 'float *' and 'double')

错误消息准确说明了问题所在。 startAmt 的类型为 float *，.01 的类型为 double。您不能将指针与数字进行比较，您需要做的是取消引用指针以获取值。在变量前放置一个 * 表示您想要获取所指向的值。

if (*startAmt < .01)

warning: passing argument 1 of 'exit' makes integer from pointer without a cast [enabled by default]

在这种情况下，您将一个指向字符数组的指针(例如“起始金额必须至少为一美分。\n退出”)传递给需要整数的 exit。

您可能想做类似的事情:

if (startAmt < .01) {
   printf("Starting amount must be at least one cent.\nExiting");
   exit(10);
}

我仅以 10 为例，它将是程序完成时返回给操作系统的数字。

请注意，当输入不正确时退出程序不太友好。