strcat

• Appends a copy of the source string to the destination string. The terminating null character in destination is overwritten by the first character of source, and a null-character is included at the end of the new string formed by the concatenation of both in destination.

• 後附 src 所指向的空終止字節字符串的副本到 dest 所指向的空終止字節字符串的結尾。字符 src[0] 替換 dest 末尾的空終止符。產生的字節字符串是空終止的。

• 若目標數組對於 src 和 dest 的內容以及空終止符不夠大，則行為未定義。
• 若字符串重疊，則行為未定義。
• 若 dest 或 src 不是指向空終止字節字符串的指針，則行為未定義。

char * strcat ( char * destination, const char * source );

Parameters

destination

• Pointer to the destination array, which should contain a C string, and be large enough to contain the concatenated resulting string.
• 指向要後附到的空終止字節字符串的指針

source

• C string to be appended. This should not overlap destination.
• 指向作為復制來源的空終止字節字符串的指針

Return Value

• destination is returned.
• 該函數返回一個指向最終的目標字符串 dest 的指針。

Example

//
// Created by zhangrxiang on 2018/2/3.
//

#include <stdio.h>
#include <string.h>

int main() {
  char str[] = "Hello C"
 
;
  char str2[50] = "Hello World";
  printf("%s\n", str);//Hello C
  printf("%s\n", str2);//Hello World
  char *str3 = strcat(str2, str);
  printf("%s\n", str2);//Hello WorldHello C
  printf("%s\n", str3);//Hello WorldHello C
  str3 = "hi everyone";
  printf("%s\n", str3);//hi everyone
  printf("%s\n", str2);//Hello WorldHello C
  str2[2] = 'L';
  str[2] = 'L';
  str[0] = 'h';
  printf("%s\n", str2);//HeLlo WorldHello C
  printf("%s\n", str);//heLlo C

  char *str4 = "hi world";
//  str[0] = 'H'; //行為為定義 h
  printf("%c\n",str4[0]);//h
  printf("%s\n",str4);

  char str5[80];
  strcpy (str5,"these ");
  strcat (str5,"strings ");
  strcat (str5,"are ");
  strcat (str5,"concatenated.");
  puts (str5);
  //these strings are concatenated.

  return 0;
}

文章參考

• http://www.cplusplus.com/reference/cstring/strcat/
• http://zh.cppreference.com/w/c/string/byte/strcat
• https://linux.die.net/man/3/strcat

C 標準庫 - string.h之strcat使用