Point cloud Library Cluster Extraction

Question

I am using point cloud library, here I have made clusters of my cloud. Now I need to load clusters one by one in my program for further analysis

for (i=0; i<= total number of clusters ;i++)
{
    cloud=cluster_cloud_i;
    further processing ..
}

I am unable to find any method to load cluster_cloud_i , it gives me syntax error. For instance, I have two clusters named cluster_cloud_1.pcd and cluster_cloud_1.pcd .

Please help me to resolve this issue