Append to the end of a Char array in C

Question

Is there a command that can append one array of char onto another   Something that would theoretically work like this     array1 has already been set to  The dog jumps     array2 has already been set to  over the log   append array2 array1   cout  lt  lt  array1     would output  The dog jumps over the log     This is a pretty easy function to make I would think  I am just surprised there isn t a built in command for it    Edit  I should have been more clear  I didn t mean changing the size of the array   If array1 was set to 50 characters  but was only using 10 of them  you would still have 40 characters to work with   I was thinking an automatic command that would essentially do     assuming array1 has 10 characters but was declared with 25 and array2 has 5 characters int i 10  int z 0      do      array1 i    array2 z         i        z   while array z       0      I am pretty sure that syntax would work  or something similar

User · Answer

If your arrays are character arrays which seems to be the case   You need a strcat    Your destination array should have enough space to accommodate the appended data though   In C    You are much better off using std  string and then you can use std  string  append

User · Answer

If you are not allowed to use C   s string class  which is terrible teaching C   imho   a raw  safe array version would look something like this    include  lt cstring gt   include  lt iostream gt   int main         char array1     The dog jumps        char array2      over the log       char   newArray   new char std  strlen array1  std  strlen array2  1       std  strcpy newArray array1       std  strcat newArray array2       std  cout  lt  lt  newArray  lt  lt  std  endl      delete    newArray      return 0      This assures you have enough space in the array you re doing the concatenation to  without assuming some predefined MAX SIZE  The only requirement is that your strings are null-terminated  which is usually the case unless you re doing some weird fixed-size string hacking   Edit  a safe version with the  enough buffer space  assumption    include  lt cstring gt   include  lt iostream gt   int main         const unsigned BUFFER SIZE   50      char array1 BUFFER SIZE       std  strncpy array1   The dog jumps    BUFFER SIZE-1     -1 for null-termination     char array2      over the log       std  strncat array1 array2 BUFFER SIZE-strlen array1 -1     -1 for null-termination     std  cout  lt  lt  array1  lt  lt  std  endl      return 0

User · Answer

You should have enough space for array1 array and use something like strcat to contact array1 to array2   char array1 BIG ENOUGH   char array2 X                               check array bounds                              strcat array1  array2

User · Answer

There s no built-in command for that because it s illegal  You can t modify the size of an array once declared   What you re looking for is either std  vector to simulate a dynamic array  or better yet a std  string   std  string first   The dog jumps     std  string second   over the log    std  cout  lt  lt  first   second  lt  lt  std  endl

[c++] Append to the end of a Char array in C++

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