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

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