For C programming I made this nested loop that is supposed to read a file and fprint when the certain number is reached. However, It seems that the file isn't read completly and its search in the lines becomes inconsistent and it varies depending on which loop rotation it is on. Can someone tell me whats wrong?

This is the output from the printf that counts the value of x to check which line it is in after each iteration:

1234567891011121314151617181920211234567891011121314151617181920212212345678910111234567891011121314151617181920212223241234567891011121314151617181234567891011121314151617181920

and this is the file with the lines:

char line [500]; int i; //iterate labels found for (1 = 0; 1