1 /*************************************************************************
2 > File Name: test.cpp
3 ************************************************************************/
4 #include"stdlib.h"
5 #include"stdio.h"
6 #include"string.h"
7
8 char *mystrcat(char *dest,const char *src)
9 {
10 char* temp = dest;
11 while(*dest != '\0')
12 {
13 dest++;
14 }
15
16 while((*dest++ = *src++) != '\0');
17
18 return temp;
19 }
20 char *mystrncat(char *dest,const char *src,size_t n)
21 {
22
23 char* temp = dest;
24 while(*dest != '\0')
25 {
26 dest++;
27 }
28
29 while(n-->0 && (*dest++ = *src++) != '\0');
30
31 return temp;
32 }
33
34
35
36 void* mymemset(void *s, int c, size_t n )
37 {
38 unsigned char uc = c;
39 unsigned char *su = (unsigned char*)s;
40 while(n-->0)
41 {
42 *su = uc;
43 su++;
44 }
45 }
46
47 int mystrlen(const char* str)
48 {
49 return *str?(mystrlen(++str)+1):0;
50 /*
51 const char* eos = str;
52 while(*eos++);
53 return (eos-str-1);
54 */
55 }
56
57 void* mymemcpy(void*dst, const void* src,size_t size)
58 {
59
60 if(src==NULL || dst==NULL) return NULL;
61 void* ret = dst;
62 while(size--)
63 {
64 *(char*)dst = *(char*)src;
65 dst = (char*)dst + 1;
66 src = (char*)src + 1;
67 }
68 return ret;
69 }
70
71 void* mymemmove(void*dst, const void* src,size_t size)
72 {
73 if(src==NULL || dst==NULL) return NULL;
74 char* psrc;
75 char* pdst;
76 //存在覆盖，自后向前进行拷贝
77 if((src<dst) && (char*)src+size > (char*)dst)
78 {
79 psrc = (char*)src + size-1;
80 pdst = (char*)dst + size-1;
81 while(size--)
82 *pdst-- = *psrc--;
83 }
84 else
85 {
86 psrc = (char*)src;
87 pdst = (char*)dst;
88 while(size--)
89 {
90 *pdst++ = *psrc++;
91 }
92 }
93 }
94
95 int mymemcmp(const void * ptr1, const void * ptr2, size_t num)
96 {
97 if(ptr1==NULL || ptr2==NULL || num<0) return 0;
98
99 char* pch1 = (char*)ptr1;
100 char* pch2 = (char*)ptr2;
101
102 while(num-- && *pch1++ == *pch2++);
103 return (pch1-pch2)<<8;
104 }
105
106 int mystrcmp ( const char * str1, const char * str2 )
107 {
108 if(str1==NULL || str2 ==NULL) return 0;
109
110 while(*str1 == *str2)
111 {
112 str1++;
113 str2++;
114 }
115
116 return (*str1-*str2);
117 }
118
119 int mystrncmp( const char * str1, const char * str2, size_t num )
120 {
121
122 if(str1==NULL || str2 ==NULL) return 0;
123
124 while(num-- && *str1 == *str2)
125 {
126 str1++;
127 str2++;
128 }
129
130 return (*str1-*str2);
131 }
132
133 int main()
134 {
135 char ch1[] = "hello";
136 char ch2[] = "herld";
137 // printf("strcat : %s\n", mystrncat(ch1,ch2,2));
138
139 printf("%d\n",mystrcmp(ch2,ch1));
140
141 printf("%d\n",mystrncmp(ch2,ch1,4));
142
143
144 return 0;
145 }
