java - 将我的 Java 代码正确转换为 C (错误 : no matching function for call to 'power1' )

Question

我用 Java 编写了这个递归程序，但将其转换为 C 时遇到问题。(刚刚开始学习 C)

我的java代码

public class Power
{
  static int count;

  public static void main( String[] args )
  {
    double[] base = { 1.4, 1.3, 1.2, 1.1, 1.0 };
    int[]      index = { 5, 20, 63, 73, -1 };
    double   value;

    System.out.println( "\nTest two algorithms for powering\n" );
    for( int i=0 ; i<base.length ; i++ )
    {
      count = 0;
      value = power1( base[i], index[i] );
      System.out.println( "1: " + base[i] + "^" + index[i] + " = " + value + ", used " + count + " multiplies" );

      count = 0;
      value = power2( base[i], index[i] );
      System.out.println( "2: " + base[i] + "^" + index[i] + " = " + value + ", used " + count + " multiplies" );
      System.out.println();
    }


  }

  public static double power1( double base, int index )
  {
    double retValue;

    assert( index>=0 );

    if( index == 0 )
    {
      retValue = 1;
    }
    else
    {
      retValue = base * power1( base, index-1 );
      count++; 
    }

    return retValue;
  }

  public static double power2( double base, int index )
  {
    double retValue;
    double temp;

    assert( index>=0 );

    if( index == 0 )
    { 
      retValue = 1;
    }
    else if( index%2 == 1 )
    {
      retValue = base * power2( base, index-1 );
      count++;
    }
    else
    {
      temp = power2( base, index/2 );
      retValue = temp*temp;
      count++;
    }

    return retValue;
  }
}

我正在处理的 C 代码...

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

//#define count;
#define ARRAY_LENGTH 5

static int count;

double power1(double base, int index);
double power2(double base, int index);

int main(int argc, char *argv[]){
    double base[5] = {1.4, 1.3, 1.2, 1.1, 1.0};
    int index[5] = {5, 20, 63, 73, -1};
    double value;

    printf("%s\n", "test two algorithms for powering\n" );
    for(double i = 0; i < ARRAY_LENGTH; i++){
        count = 0;
        //value = power1(base[i], index[i]);
        value = power1(base, index);

        printf("1: %f^%d = %f, used %d multiples", base,index,value,count);

        count =0;

        value = power2(base, index);

        printf("2: %f^%d = %f, used %d multiples", base[i],index[i],value,count);

    }




}

double power1(double base[5], int index[5]){
    double retValue;
    double temp;

    assert(index>=0);

    if(index ==0){
        retValue=1;
    }else if(index%2 ==1){
        retValue = base * power2(base, index-1);
        count++;
    }else{
        temp = power2(base, index/2);
        retValue = temp * temp;
        count++;
    }

    return retValue;
}


double power2(double base[5], int index[5]){
    double retValue;
    double temp;

    assert(index >=0);

    if(index ==0){
        retValue=1;

    }else if( index %2 ==1){
        retValue = base * power2(base, index-1);
        count++;
    }else{
        temp = power2(base, index/2);
        retValue = temp * temp;
        count++;
    }
    return retValue;
}

这些是我的错误和警告(其中大部分是重复的):

/Users/elle/Desktop/power.c:22:11: error: no matching function for call to 'power1'
                value = power1(base, index);
                        ^~~~~~
/Users/elle/Desktop/power.c:10:8: note: candidate function not viable: no known conversion from 'double [5]' to 'double' for 1st argument
double power1(double base, int index);
       ^
/Users/elle/Desktop/power.c:25:46: warning: format specifies type 'double' but the argument has type 'double *' [-Wformat]
                printf("1: %f^%d = %f, used %d multiples", base,index,value,count);
                           ~~                              ^~~~
/Users/elle/Desktop/power.c:25:51: warning: format specifies type 'int' but the argument has type 'int *' [-Wformat]
                printf("1: %f^%d = %f, used %d multiples", base,index,value,count);
                              ~~                                ^~~~~
/Users/elle/Desktop/power.c:29:11: error: no matching function for call to 'power2'
                value = power2(base, index);
                        ^~~~~~
/Users/elle/Desktop/power.c:11:8: note: candidate function not viable: no known conversion from 'double [5]' to 'double' for 1st argument
double power2(double base, int index);
       ^
/Users/elle/Desktop/power.c:32:50: error: array subscript is not an integer
                printf("2: %f^%d = %f, used %d multiples", base[i],index[i],value,count);
                                                               ^~
/Users/elle/Desktop/power.c:32:59: error: array subscript is not an integer
                printf("2: %f^%d = %f, used %d multiples", base[i],index[i],value,count);
                                                                        ^~
/Users/elle/Desktop/power.c:49:16: error: invalid operands to binary expression ('int *' and 'int')
        }else if(index%2 ==1){
                 ~~~~~^~
/Users/elle/Desktop/power.c:50:21: error: no matching function for call to 'power2'
                retValue = base * power2(base, index-1);
                                  ^~~~~~
/Users/elle/Desktop/power.c:11:8: note: candidate function not viable: no known conversion from 'double *' to 'double' for 1st argument; dereference the argument with *
double power2(double base, int index);
       ^
/Users/elle/Desktop/power.c:53:28: error: invalid operands to binary expression ('int *' and 'int')
                temp = power2(base, index/2);
                                    ~~~~~^~
/Users/elle/Desktop/power.c:71:18: error: invalid operands to binary expression ('int *' and 'int')
        }else if( index %2 ==1){
                  ~~~~~ ^~
/Users/elle/Desktop/power.c:72:19: error: invalid operands to binary expression ('double *' and 'double')
                retValue = base * power2(base, index-1);
                           ~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~
/Users/elle/Desktop/power.c:75:28: error: invalid operands to binary expression ('int *' and 'int')
                temp = power2(base, index/2);
                                    ~~~~~^~
2 warnings and 10 errors generated.
[Finished in 0.1s with exit code 1]

输出应该是这样的

Test two algorithms for powering

1: 1.4^5 = 5.378239999999998, used 5 multiplies
2: 1.4^5 = 5.378239999999998, used 4 multiplies

1: 1.3^20 = 190.04963774880824, used 20 multiplies
2: 1.3^20 = 190.04963774880818, used 6 multiplies

1: 1.2^63 = 97368.50480227199, used 63 multiplies
2: 1.2^63 = 97368.50480227212, used 11 multiplies

1: 1.1^73 = 1051.1531995000591, used 73 multiplies
2: 1.1^73 = 1051.1531995000587, used 9 multiplies

Exception in thread "main" java.lang.AssertionError
    at Power.power1(Power.java:31)
    at Power.main(Power.java:15)

我在大多数情况下都将 java 与 c 混合在一起，几个小时以来我一直在寻找如何修复这些错误。

如有任何帮助，我们将不胜感激!

Answer 1

您并不是想将数组传递给您的函数:

double power1(double base[5], int index[5])

与Java版本不匹配:

public static double power1( double base, int index )

应该很简单:

double power1(double base, int index)

与power2相同。

不知何故，你的声明是正确的，但定义是错误的。

您还需要执行 value = power1( base[i], index[i] ); 就像 Java 版本中一样。