strcat函数原型,strncat函数常见报错

/*原型：extern char *strncat(char *dest,char *src,int n);用法：#include <string.h>功能：把src所指字符串的前n个字符添加到dest结尾处（覆盖dest结尾处的''）并添加''。说明：src和dest所指内存区域不可以重叠且dest必须有足够的空间来容纳src的字符串。返回指向dest的指针。*/#include <stdio.h>#include <string.h>char *strncat(char *dst, const char *src, size_t n){ if (n != 0) { //保存两个操作字符串的首地址 char *d = dst; const char *s = src; //将指向dst的指针d移到字符串末尾,指向'' while (*d != 0) d++; //复制过程 do { //如果到达了src字符串的末尾,则复制终止 if ((*d = *s++) == 0) break; //移向下一个元素 d++; } while (--n != 0); //复制后剩余要复制的元素个数 *d = 0; //复制完毕后,将最后一个元素置为'' } return dst; }int main() { char str[50] = "Hello "; char str2[50] = "World!"; strcat(str, str2); strncat(str, " Goodbye World!", 3); puts(str);}

 

 

//linux源码

#ifndef __HAVE_ARCH_STRNCAT /** * strncat - Append a length-limited, %NUL-terminated string to another * @dest: The string to be appended to * @src: The string to append to it * @count: The maximum numbers of bytes to copy * * Note that in contrast to strncpy(), strncat() ensures the result is * terminated. */ char *strncat(char *dest, const char *src, size_t count) { char *tmp = dest; if (count) { while (*dest) dest++; while ((*dest++ = *src++) != 0) { if (--count == 0) { *dest = ''; break; } } } return tmp; } EXPORT_SYMBOL(strncat); #endif

 

 

//标准C源码

/****strncat.c - append n chars of string to new string** Copyright (c) 1985-1997, Microsoft Corporation. All rights reserved.**Purpose:* defines strncat() - appends n characters of string onto* end of other string********************************************************************************/#include <cruntime.h>#include <string.h>/****char *strncat(front, back, count) - append count chars of back onto front**Purpose:* Appends at most count characters of the string back onto the* end of front, and ALWAYS terminates with a null character.* If count is greater than the length of back, the length of back* is used instead. (Unlike strncpy, this routine does not pad out* to count characters).**Entry:* char *front - string to append onto* char *back - string to append* unsigned count - count of max characters to append**Exit:* returns a pointer to string appended onto (front).**Uses:**Exceptions:********************************************************************************/char * __cdecl strncat ( char * front, const char * back, size_t count ){ char *start = front; while (*front++) ; front--; while (count--) if (!(*front++ = *back++)) return(start); *front = ''; return(start);}