#include <stdio.h>
 
void cat_data(int *data1,const int *data2,int len2,int max1) {
    int len1=0;
    while (len1<max1&&data1[len1]!=0) {
        len1++;
    }
 
    for (int i= 0;i<len2&&(len1+i)<max1-1;i++) {
        data1[len1+i]=data2[i];
    }
 
    data1[len1+len2] = 0;
}
 
int main(void) {
    int data1[7] = {1,2};   
    int data2[5] = {3,4,5,6,7};
    cat_data(data1, data2, 5,8 );
    for (int i=0;data1[i]!=0;i++) {
        printf("data1[%d] = %d\n",i,data1[i]);
    }
    return 0;
}

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