#include <stdio.h>
void cat_data(int *data1,const int *data2,int len2);
 
int main(void) {
 
 int data1[7]={1,2};
 int data2[5]={3,4,5,6,7};
 int len1 = sizeof(data1)/sizeof(data1[0]);
 int len2 = sizeof(data2)/sizeof(data2[0]);
 
 cat_data(&data1,&data2,len2);
 
 for(int i=0; i<len1; i++)
  printf("data1[%d]=%d\n",i,data1[i]);
 
 return 0;
}
void cat_data(int *data1,const int *data2,int len2){
 
 while(*data1){
  data1++;
 }
 
 while(len2--){
  *data1++=*data2++;
 }
}

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