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

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