无法让字符串搜索正常工作

Question

我正在编写一个简单的程序，从控制台获取用户输入以计算电阻器的电阻值，其中一部分涉及将用户输入与预定字符串列表进行比较。

我已经弄清楚了其中的大部分内容(至少我是这么认为的)，但是每当我调用“搜索”函数时，它应该返回与输入匹配的字符串数组的索引，否则返回 -1 .问题是，每当我在适当的程序中调用它时，它总是返回 -1，因此即使不是，程序也会打印“无效颜色”。我不确定问题出在哪里，我想知道我能做些什么。

这是有问题的程序:

#include <stdio.h>
#include <math.h>
#include <string.h>

char COLOR_CODES[10][7] = {"black", "brown", "red", "orange", "yellow", "green", "blue", "violet", "gray", "white"};
int COMPARE_LIMIT = 7;

int search(char array[10][7], int size, char target[7]);

int main(void)
{
  //used for repeating input menu
  int menu = 0;
  char menuChoice = 0;

  //string variables hold input colors.
  char band1[7];
  char band2[7];
  char band3[7];

  //int variables hold int values of subscript for bands 1-3
  int value1;
  int value2;
  int value3;

  //value of resistor in ohmn
  int ohms;

  //holds value of multiplier for third band
  int powerMultiplier;

  while(menu == 0)
  {
    printf("Enter the colors of the resistor's three bands,\n");
    printf("beginning with the band nearest the end. Type\n");
    printf("the colors in lowercase letters only. NO CAPS\n");
    printf("OR SPACES.\n");

    printf("Band 1:");
    scanf("%s", &band1);
    printf("Band 2:");
    scanf("%s", &band2);
    printf("Band 3:");
    scanf("%s", &band3);

    if(search(COLOR_CODES, 10, band1) == -1)
    {
      printf("Invalid Color: %s\n", band1);
    }

    else if(search(COLOR_CODES, 10, band2) == -1)
    {
      printf("Invalid Color: %n\n", band2);
    }

    else if(search(COLOR_CODES, 10, band3) == -1)
    {
      printf("Invalid Color: %s\n", band3);
    }

    else
    {
      value1 = search(COLOR_CODES, 10, band1);
      value2 = search(COLOR_CODES, 10, band2);
      value3 = search(COLOR_CODES, 10, band3);

      powerMultiplier = (int)pow(10, value3);

      ohms = (value1 * 10) + value2;
      ohms = ohms * powerMultiplier;

      if(ohms < 1000)
      {
        printf("Resistance value: %s ohms", ohms);
      }

      else
      {
        int kiloOhms = (ohms / 1000);
        printf("Resistance value: %s kilo-ohms", kiloOhms);
      }

      printf("Do you want to decode another resistor? (y/n)");
      scanf("%c", &menuChoice);

      while(menuChoice != 'y' && menuChoice != 'Y' && menuChoice != 'n' && menuChoice != 'N')
      {
        if(menuChoice != 'Y' && menuChoice != 'y')
        {
          if(menuChoice == 'N' || menuChoice == 'n')
          {
            menu = 0;
          }

          else
          {
            printf("Invalid choice.");
          }
        }
      }
    }
  }

  return 0;
}

//returns the subscript of array[][] that matches target[].
int search(char array[10][7], int size, char target[7])
{
  int n;
  for (n = 0; n < size; n++)
  {
    if (strncmp(array[n], target, COMPARE_LIMIT) == 0)
    {
      return n;
    }

    else
    {
      return -1;
    }
  }
}

Answer 1

您的 search() 函数在仅查看列表中的第一项后返回 -1。所以它可能会找到 black 但不会找到其他任何东西。建议修改如下:

int search(char array[10][7], int size, char target[7])
{
  int n;
  for (n = 0; n < size; n++)
  {
    if (strncmp(array[n], target, COMPARE_LIMIT) == 0)
    {
      return n;
    }
  }
  return -1;
}

这样，for 循环将在确定您键入的内容未找到并返回 -1 之前运行完成。