+ 1

# how to merge two arrays in C???

12th Dec 2020, 9:47 PM
Aleks kryzhanivskyi
+ 4
Mirielle[ INACTIVE ] that's simply not true, you can easily do it using memcpy. as rodwynnejones has stated, you need an array that have enough space for the total amount of the 2 arrays. here is how you can do it in C. #include <stdio.h> #include <string.h> int main(){ int a[10] = {1, 2, 3}; int b[10] = {4, 5, 6}; int aLen = 3, bLen = 3; memcpy(a + aLen, b, sizeof(int) * bLen); printf("a = "); for (int i=0; i<(aLen+bLen); i++){ printf("%d ", a[ i ]); } return 0; } >>> a = 1 2 3 4 5 6
12th Dec 2020, 11:01 PM
Shen Bapiro
+ 3
here is a way (just for playing around ;) #include <stdio.h> #include <alloca.h> #include <stddef.h> static int* mergeStack(int* a, size_t aS, int* b, size_t bS) { // error check // ... int* ret = alloca((aS + bS) * sizeof(int)); if (ret == NULL) { return ret; } for (int i = 0; i < aS; i++) { ret[i] = a[i]; } for (int i = 0; i < bS; i++) { ret[i+aS] = b[i]; } return ret; } int main() { int a[] = { 1, 2, 3 }; int b[] = { 4, 5, 6 }; int* x = mergeStack(a, 3, b, 3); for (int i = 0; i < 6; i++) { printf("%d\n", x[i]); } return 0; } // out: 1 2 3 4 5 6
12th Dec 2020, 10:47 PM
Flash
+ 2
What do you mean by merging?
14th Dec 2020, 7:30 AM
Sonic
+ 1
You need to make the third array large enough to hold them both, use a for loop for each array and assign to the third...but...initialise/declare the increment variable outside the loops. I should of asked really...how do you want them merged? example:- int arr1[] = {1,2,3,4,5}; int arr2[] = {6,7,8,9,10}; int size = sizeof arr1/ sizeof arr1[0]; int arr3[size * 2]; int i; for(i = 0; i < size; i++) arr3[i] = arr1[i]; for(int j = 0 ; j < size; i++, j++) arr3[i] = arr2[j]; for(i = 0 ; i < size * 2; i++) printf("%d ", arr3[i]);
12th Dec 2020, 10:43 PM
rodwynnejones
+ 1
...or int arr1[] = {1,2,3,4,5}; int arr2[] = {6,7,8,9,10}; int size = sizeof arr1/ sizeof arr1[0]; int arr3[size * 2]; for(int i = 0; i < size; i++){ arr3[i] = arr1[i]; arr3[i + size] = arr2[i]; } for(int i = 0 ; i < size * 2; i++) printf("%d ", arr3[i]);
12th Dec 2020, 11:01 PM
rodwynnejones
+ 1
thanks)π€
12th Dec 2020, 11:19 PM
Aleks kryzhanivskyi
+ 1
While Flash's answer is nice, the use of `alloca` should not be used when dealing with enormous amounts of data as it allocates memory to the stack. Also note that `alloca` is not part of any standard. It is not part of C nor is it part of POSIX. More info on `alloca` can be found here: https://www.man7.org/linux/man-pages/man3/alloca.3.html
14th Dec 2020, 12:08 PM
luΚi
0
i know that it possible
12th Dec 2020, 10:38 PM
Aleks kryzhanivskyi
0
kind if it is array1(123456) and the second array2(789) and when combine.it will be array(123456789)
12th Dec 2020, 10:46 PM
Aleks kryzhanivskyi
0
thank you very much
12th Dec 2020, 10:49 PM
Aleks kryzhanivskyi
0
ππ»
12th Dec 2020, 10:50 PM
Aleks kryzhanivskyi
0
Rodwynnejones,what do you mean can you explain?this(int size=sizeof arr1/size of arr1[0] ??because i wrote in code(int r=n/arr1[0]) and it doesnt work correctly
13th Dec 2020, 12:10 PM
Aleks kryzhanivskyi
0
sizeof is an operator that returns size of an object/type in bytes Aleks kryzhanivskyi
13th Dec 2020, 12:46 PM
Flash
0
γγ°γγΎγͺζΏ as I said, it was for fun
14th Dec 2020, 1:03 PM
Flash
- 5
You cannot
12th Dec 2020, 10:30 PM
Mirielle