C file calls the executable file

The c file calls the executable file-general Linux technology-Linux technology and application information. The following is a detailed description. Cainiao asked for help !!!
I wrote a. c file and compiled it into an executable file using gcc. Then, I used another. c file named ceshi to execute this executable file using the ceshi file. The question is:
1: The executable file has an interface with the outside world, that is, I can enter a value;
2: Can I automatically enter a value in the ceshi file and pass it to the executable file ??? How to Do This ?;
3: Compile ceshi into an executable file to automatically input and traverse the content I want;
I hope you can tell me what I mean? The description may be unclear.