C語言實現過濾ASCII在0~127範圍內的字符，並去除重複的字符

 1 #include <stdio.h>
 2 #include <string.h>
 3 /*
 4 1.以字符串做爲參數
 5 2.找出ASCII在1~127範圍內的字符
 6 3.去掉重複字符 
 7 */
 8 
 9 int GetString(char *str);
10 
11 int main(int argc, char *argv[])
12 {
13     char ch[] = "abcd123123123123123123";
14     int num = 0;
15     
16     num = GetString(ch);
17     
18     printf("num = %d\n", num);
19     return 0;
20 } 
21 
22 int GetString(char *str)
23 {
24     /*第一步：先計算符合範圍的ASCII*/
25     unsigned int index;
26     unsigned int n = 0;
27     unsigned int i = 0, j, k = 0;  
28     char flag; 
29     char arr[strlen(str)];
30     char newchar[strlen(str)];
31     
32     for(index = 0; index < strlen(str); index++)
33     {
34         if((str[index] >= 0) && (str[index] <= 127))
35         {
36             arr[n] = str[index];
37             n++;
38         }        
39     } 
40     
41     while(arr[i] != '\0')  
42     {  
43         flag = 1;  
44         for(j = 0; j < i; j++)  
45         {  
46             if(arr[i] == newchar[j])  
47             {
48                 flag = 0;  
49             }     
50         }  
51         if(flag)  
52         {
53             newchar[k] = arr[i];
54             k++;
55         }
56               
57           i++;  
58     }    
59      
60     newchar[k]='\0';  
61     puts(newchar);  
62     
63     return k;
64 }