Program. Software. Application. Process. These are all terms that describe different aspects of a similar thing.
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\nSoftware is the big category. Application is being redefined, thanks to mobile devices, although for a computer I use the term to refer to a software category, such as word processing.<\/p>\n
A program is code designed to do something, although a single program can involve many different things happening at once. That’s where the term process<\/em> comes into play.<\/p>\n A process is a task performed in a computer. The operating system manages all the different processes, which run at the same time in a manner I shan’t bother describing.<\/p>\n When you code a C program, you’re creating something that runs as a single process. Start the program and the operating system launches the process, assigning it an ID and managing its resources.<\/p>\n To view your program’s process ID, use the getpid()<\/em> function. The function returns an integer value of the pid_t<\/em> type and it requires inclusion of the The getpid()<\/em> function fetches the assigned process ID. The result is displayed, similar to this output:<\/p>\n Of course, the process ID number differs from system to system, and it may change each time you run the code, but it’s unique for each running process.<\/p>\n While this information may seem nice and all that, it does serve a purpose: Your program need not limit itself to a single process. It’s entirely possible for one program to run multiple processes. The process ID is how you keep track of each one. In next week’s Lesson<\/a>, I’ll present code that runs two different processes — essentially a single program that multitasks.<\/p>\n","protected":false},"excerpt":{"rendered":" The big deal on programs and processes. Continue reading unistd.h<\/code> header file. Here’s sample code:<\/p>\n\r\n#include <stdio.h>\r\n#include <unistd.h>\r\n\r\nint main()\r\n{\r\n pid_t process;\r\n\r\n process = getpid();\r\n printf(\"This program has a process ID of %d\\n\",process);\r\n\r\n return(0);\r\n}<\/pre>\nThis program has a process ID of 900<\/code><\/pre>\n