实现strlen,strcpy,strcat,strcmp同功能的函数stringLength,stringCopy,stringCatch,stringCompare

 1 #import <Foundation/Foundation.h>
 2 
 3 /*
 4     求字符串长度
 5  */
 6 int stringLength(char arr[]);
 7 
 8  
 9 /*
10 复制字符串
11  将arr1 复制到 arr
12  */
13 void stringCopy(char arr[],char arr1[]);
14 
15 
16    
17 /*
18  拼接字符串
19  将arr1 加到 arr 后
20  */
21 void stringCatch(char arr[],char arr1[]);
22 
23 
24 /*
25  比较字符串
26  */
27 int stringCompare(char arr[],char arr1[]);

 1 #import "FunctionOfArray.h"
 2 
 3 int stringLength(char arr[]){
 4     int length = 0;
 5     while (arr[length] != ‘\0‘) {
 6         length++;
 7     }
 8     return length;
 9 }
10 
11 
12 void stringCopy(char arr[],char arr1[]){
13     int i = 0;
14     while (arr1[i] != ‘\0‘) {
15         arr[i] = arr1[i];
16         i++;
17     }
18     arr[i] = ‘\0‘;
19 }
20 
21 void stringCatch(char arr[],char arr1[]){
22     int k = stringLength(arr);
23     int j = stringLength(arr1);
24     for (int i = 0; i < j; i++) {
25         arr[k+i] = arr1[i];
26     }
27     arr[k + j] = ‘\0‘;
28 }
29 
30 int stringCompare(char arr[],char arr1[]){
31     int k = stringLength(arr);
32     int j = stringLength(arr1);
33     
34     for (int i = 0; i < k && i< j; i++) {
35         if(arr[i] != arr1[i]){
36             return (int)arr[i] - (int)arr1[i];
37         }
38     }
39     if(k == j){
40         return 0;
41     }else if(k > j ){
42         return (int)arr[j] - (int)arr1[j];
43     }else{
44         return (int)arr[k] - (int)arr1[k];
45     }
46 }