返回指针不能正常工作

当我试图通过函数返回的指针显示数组的内容时，程序只显示零。我不确定缺少了什么。我试着检查了几次是什么问题，但似乎没有线索。我正在使用devc++。代码如下。非常感谢您的帮助。

#include <iostream>
#include <math.h>
#include <cstdlib>
#include <cstring>
using namespace std;
bool vowel(char c)
{
int i, val;
char alphabet[52]={'a','A','b','B','c','C','d','D','e','E','f','F','g','G','h','H','i','I','j','J','k','K','l','L','m','M','n','N','o','O','p','P','q','Q','r','R','s','S','t','T','u','U','v','V','w','W','x','X','y','Y','z','Z'};
 int const is_vowel[52]={1,1,0,0,0,0,0,0,1,1,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,1,1,0,0};
    for (i=0;i<52;i++)
    if (c!=alphabet[i])
    {   
    val=is_vowel[i];
    return val;
    }       
}
bool consonant(char c)
{
    int i, val;
char alphabet[52]={'a','A','b','B','c','C','d','D','e','E','f','F','g','G','h','H','i','I','j','J','k','K','l','L','m','M','n','N','o','O','p','P','q','Q','r','R','s','S','t','T','u','U','v','V','w','W','x','X','y','Y','z','Z'};
     int const is_coson[52]={1,1,0,0,0,0,0,0,1,1,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,1,1,0,0};
    for (i=0;i<52;i++)
    if (c==alphabet[i])
    {   
    val=is_coson[i];
    return val;
    }       
}
int* scan(char* sentence, int len_sent)
{
    char c;
int count_cons=0, count_vow=0, count_dig=0, count_lc=0, count_uc=0, i,j;
int con_value, vow_value;
int* ptr; 
int array_all_counts[5];
for (i=0; i<len_sent; i++)
{
    c=sentence[i];
    //check if the c is a digit
    if (c>=48 && c<=57)
        count_dig++;
    else if (isalpha(c))
    {
        con_value=consonant(c);
        vow_value=vowel(c);
        if (con_value==0)
            count_cons++;
        else if (vow_value!=0)  //vow_value==1
            count_vow++;
        if (96<c && c<123)
             count_lc++;
        if (64<c && c<91)
             count_uc++;                   
    }
}
cout<<"n-------------------"<<endl;
array_all_counts[0]=count_uc;
array_all_counts[1]=count_lc;
array_all_counts[2]=count_dig;
array_all_counts[3]=count_vow;
array_all_counts[4]=count_cons;
    ptr=array_all_counts;

    cout<<"nnnTesting the output of pointer: "<<endl;
    for (i=0; i<5; i++)
      cout<<ptr[i]<<"  ";
return ptr;
}

int main()
{
    int j, length;
char sentence[256];
int* ptr_array;  
cout<<"Please, enter a sentence; ";
cin.getline(sentence,256);
length=strlen(sentence);
cout<<"the sentence: ";
cout<<sentence<<endl;
ptr_array=scan(sentence, length);  //Address of first element returned into ptr_array
cout<<endl;
/// cout<<"Upper case: "<<" Lower case: "<<" Digits: "<<" Vowels: "<<" Consonants: "<<endl;
for (j=0; j<5; j++)
    cout<<ptr_array[j]<<"  ";  //Where the problem is...
return 0;
}