Introduction - If you have any usage issues, please Google them yourself
Statement and to give the initial value. j, k as the loop counter not only to declare the initial value assigned. The first cycle j from 1 to 4, control print lines internal loop from 0 to 2* j-1 (corresponding to j values 1,3,5,7, respectively), the loop control the number of printed characters printf ( " c" , i) this one the i variable by the corresponding ASCII character code corresponding to the characters to be printed