Dear Statalist

I would like to search a string "1" (stored as string) in the matrix transcribed to mata from stata. Moreover, I would like to search it row-wise and increment the column no. in the loop. The reason is that I would like to get the first row where "1" occurs (in any column).

The following is my code. Can I request your help in understanding what is the mistake here and how to get the desired output?

Code:
mata
x=st_sdata(.,.)
for(i=1;i<=rows(x);i++){
for(j=1;j<=cols(x);j++){
if(x[i,j]=="1") break
printf("i=%g\n",i)
printf("j=%g\n",j)
}
}
i
j
end

Thanks
Abhimanyu