for(int i=1; i<argc; i++){
if(strncmp(argv[i],"nb",2)==0) nb_test = atoi(&(argv[i][2])); //nb of test
if(strncmp(argv[i],"ctr",3)==0) ctr = atoi(&(argv[i][3])); //CTR ? 1 otherwise CBC like
if(strncmp(argv[i],"sizebuf",7)==0) size_buf = atoi(&(argv[i][7])); //SIZE of the buffer
if(strncmp(argv[i],"lena",4)==0) lena = atoi(&(argv[i][4])); //Use Lena or buffer
for(int i=1; i<argc; i++){
if(strncmp(argv[i],"nb",2)==0) nb_test = atoi(&(argv[i][2])); //nb of test
if(strncmp(argv[i],"ctr",3)==0) ctr = atoi(&(argv[i][3])); //CTR ? 1 otherwise CBC like
if(strncmp(argv[i],"sizebuf",7)==0) size_buf = atoi(&(argv[i][7])); //SIZE of the buffer
if(strncmp(argv[i],"lena",4)==0) lena = atoi(&(argv[i][4])); //Use Lena or buffer