如何使用C中的指针将一个数组的内容复制到另一个数组？

Question

I have three Pointers:

int *x,*y, *Temp;

And then I have done

x = (int *)malloc(sizeof(int)*m);
y = (int *)malloc(sizeof(int)*n);
Temp = (int *)malloc(sizeof(int)*(m+n));

where m and n are certain values.

Next, I have entered values into Temp.

  for(i=0; i < m+n; i++) {
  scanf("%d", Temp+i);
  }

I want half of Temp in x and the other half in y. How do I do this?

for(i=0; i < m; i++) {
  x[i] = Temp[i];
}

The code above to copy the contents is not working!

Also, how do I print the values?

Answer 1

Using memcpy is probably the easiest way to accomplish what you want:

memcpy(x, Temp, m * sizeof*Temp);
memcpy(y, &Temp[m], n * sizeof*Temp);

To print the values, just use printf :

puts("Values in x:");
for(int i = 0; i < m; ++i) {
      printf("%d\n", x[i]); 
}

puts("Values in y:");
for(int i = 0; i < n; ++i) {
      printf("%d\n", y[i]);
}

Answer 2

Use memcpy .It will copy desired numbre of bytes .

What I was doing is already mentioned in this answer of PC Luddite

Answer 3

You can use as follows to print the values. I just use M in place of m for better clarity.

for(i=0; i < M; i++) {
printf("VAL: %d\n",x[i]);
}

Similarly you can also print another array y .

Answer 4

It doesn't really look like you need to allocate all that memory, nor does it seem like you need to copy it. Consider using this alternative approach:

int* xy = malloc(sizeof(*xy) * (m+n));
int* x = xy;
int* y = xy + n;
...
free(xy);