How to display the number of elements of an array of structures in the form of a table for one of the variables of the structure? [closed]

There is a worker structure, which includes the workshop number and age. Created an array of workers with different data. It is necessary to calculate the number of employees up to 20 years old, from 20 to 30 and more than 30. Output as a table:

workshop code ..... number of employees from 20 ... 20-30 ... 30+

The difficulty arose in the fact that in the table each employee would not occupy a new line with the same workshop code, but would be added to the workshop code that already exists for his code.

struct worker { int codePid, codeCeh, tabNum, yearBirth, codeNation, famStage, workStage, workStageNep, profCode, roz; double ok; char surname[30]; }; int main() { worker w[10]; return 0; }