124 lines
2.6 KiB
C++
124 lines
2.6 KiB
C++
#include <string.h>
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size_t strlen(const char* __s)
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{
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const char* i = __s;
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for (; *i; ++i)
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;
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return (i - __s);
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}
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char* strcpy(char* dest, const char* src)
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{
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memcpy(dest, src, strlen(src) + 1);
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return dest;
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}
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char* strncpy(char* dest, const char* src, size_t n)
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{
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size_t src_len = strlen(src) + 1; // NULL byte
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memcpy(dest, src, src_len > n ? n : src_len);
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return dest;
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}
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int strcmp(const char* a, const char* b)
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{
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while (*a && (*a == *b))
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{
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a++;
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b++;
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}
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return *(const unsigned char*)a - *(const unsigned char*)b;
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}
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int strncmp(const char* a, const char* b, size_t n)
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{
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const char* base = a;
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while (*a && (*a == *b) && (size_t)(a - base) < (n - 1))
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{
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a++;
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b++;
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}
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return *(const unsigned char*)a - *(const unsigned char*)b;
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}
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char* strncat(char* dest, const char* src, size_t n)
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{
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size_t dest_len = strlen(dest);
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size_t i;
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for (i = 0; i < n && *(src + i); i++) *(char*)(dest + dest_len + i) = *(char*)(src + i);
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*(char*)(dest + dest_len + i) = '\0';
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return dest;
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}
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char* strcat(char* dest, const char* src)
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{
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size_t dest_len = strlen(dest);
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size_t i;
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for (i = 0; *(src + i); i++) *(char*)(dest + dest_len + i) = *(char*)(src + i);
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*(char*)(dest + dest_len + i) = '\0';
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return dest;
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}
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char* strstr(char* haystack, const char* needle)
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{
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size_t needle_size = strlen(needle);
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size_t haystack_size = strlen(haystack);
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while (*haystack)
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{
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if (*haystack == *needle)
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{
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if (needle_size <= haystack_size)
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{
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if (!strncmp(haystack, needle, needle_size)) return haystack;
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}
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else { return NULL; }
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}
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haystack++;
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haystack_size--;
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}
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return NULL;
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}
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void* memcpy(void* dest, const void* src, size_t n)
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{
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for (size_t i = 0; i < n; ++i) { *((char*)dest + i) = *((char*)src + i); }
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return dest;
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}
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void* memset(void* dest, int c, size_t n)
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{
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for (size_t i = 0; i < n; ++i) { *((char*)dest + i) = (char)c; }
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return dest;
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}
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int memcmp(const void* a, const void* b, size_t n)
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{
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const char* _a = (const char*)a;
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const char* _b = (const char*)b;
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for (; n && _a == _b; n--, _a++, _b++)
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;
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if (!n) return 0;
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if (*_a > *_b) return 1;
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return -1;
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}
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void* memmove(void* dest, void* src, size_t n)
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{
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if (dest == src) return dest;
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if (dest > src)
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{
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for (long i = n - 1; i >= 0; i++) { *((char*)dest + i) = *((char*)src + i); }
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}
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else
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{
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for (long i = 0; i < (long)n; i++) { *((char*)dest + i) = *((char*)src + i); }
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}
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return dest;
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} |