写的是数组内容，将已知数组拷贝到其它三个数组内，第一个数组是使用带数组表示法的函数；第二个数组是使用带指针表示法和指针递增的函数；第三个是以目标数组名、源数组名和指向源数组最后一个元素后面的元素指针的方法。
现在三种方法得到的答案都有误，以下是程序，还请各位大佬指点：
#include<stdio.h>
void copy_arr( double target1[], double source[], int num );
void copy_ptr( double *target2, double *source, int num );
void copy_ptrs( double *target3, double *start, double *end );
void out_put( double *target, int num);
int main(void)
{
    double source[5] = {1.1, 2.2, 3.3, 4.4, 5.5};
    double target1[5];
    double target2[5];
    double target3[5];
   
    copy_arr(target1, source, 5);
    copy_ptr(target2, source, 5);
    copy_ptrs(target3, source, source + 5);
    out_put(target1, 5);
    out_put(target2, 5);
    out_put(target3, 5);
   
    return 0;
}
void copy_arr( double target1[], double source[], int num )
{
    int i;
    for(i = 0; i < num; i++)
    {
        target1[i] = source[i];
    }
}
void copy_ptr( double *target2, double *source, int num )
{
    int i;
    for(i = 0; i < num; i++)
    {
        *target2 = *source;
        *target2++;
        *source++;
    }
}
void copy_ptrs( double *target3, double *start, double *end )
{
    while(*start < *end)
    {
        *target3 = *start;
        *start++;
    }
}
void out_put( double *target, int num)
{
    int i;
   
    for(i = 0; i < num; i++)
    {
        printf("%d, ", *target);
        *target++;
    }
    printf("\n");
}

已解决，新代码如下：
#include<stdio.h>
void copy_arr( double target1[], double source[], int num );
void copy_ptr( double *target2, double *source, int num );
void copy_ptrs( double *target3, double *start, double *end );
void out_put( double *target, int num);
int main(void)
{
    double source[5] = {1.1, 2.2, 3.3, 4.4, 5.5};
    double target1[5];
    double target2[5];
    double target3[5];
   
    copy_arr(target1, source, 5);
    copy_ptr(target2, source, 5);
    copy_ptrs(target3, source, source + 5);
    out_put(source, 5);
    out_put(target1, 5);
    out_put(target2, 5);
    out_put(target3, 5);
   
    return 0;
}
void copy_arr( double target1[], double source[], int num )
{
    int i;
    for(i = 0; i < num; i++)
    {
        target1[i] = source[i];
    }
}
void copy_ptr( double *target2, double *source, int num )
{
    int i;
    for(i = 0; i < num; i++)
    {
        *target2 = *source;
        *target2++;
        *source++;
    }
}
void copy_ptrs( double *target3, double *start, double *end )
{
    while(*start > *end)
    {
        *target3 = *start;
        *start++;
        *target3++;
    }
}
void out_put( double *target, int num)
{
    int i;
   
    for(i = 0; i < num; i++)
    {
        printf("%1.2lf, ", *target);
        *target++;
    }
    printf("\n");
}

1. 数组长度 及 下标 应当用 size_t 类型，而不是 int 类型

2. *target2++;
   *source++;
我猜你想要的只是
   target2++;
   source++;
当然，推荐你用正常的
   ++target2;
   ++source;

3. while(*start > *end)
我猜你想要的是 while(start > end)

#include <stdio.h>

void copy_arr( double dst[], const double src[], size_t num );
void copy_ptr( double* dst, const double* src, size_t num );
void copy_ptrs( double* dst, const double* src_begin, const double* src_end );
void out_put( const double* p, size_t num );

int main( void )
{
    double source[5] = { 1.1, 2.2, 3.3, 4.4, 5.5 };
    double target1[5];
    double target2[5];
    double target3[5];

    copy_arr( target1, source, 5 );
    copy_ptr( target2, source, 5 );
    copy_ptrs( target3, source, source+5 );

    out_put( source, 5 );
    out_put( target1, 5 );
    out_put( target2, 5 );
    out_put( target3, 5 );
}

void copy_arr( double dst[], const double src[], size_t num )
{
    for( size_t i=0; i!=num; ++i )
        dst[i] = src[i];
}

void copy_ptr( double* dst, const double* src, size_t num )
{
    for( size_t i=0; i!=num; ++i )
        *dst++ = *src++;
}

void copy_ptrs( double* dst, const double* src_begin, const double* src_end )
{
    for( ; src_begin!=src_end; )
        *dst++ = *src_begin++;
}

void out_put( const double* p, size_t num )
{
    for( size_t i=0; i!=num; ++i )
        printf( "%.2lf, ", p[i] );
    putchar( '\n' );
}