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To read a line from stdin, use the ? command. This evaluates the line as if it were a dc command, and so it is necessary that it be syntactically correct and presents a potential security problem because the ! dc command enables arbitrary command execution. As mentioned above, p prints the top of the stack with a newline after it.
By itself, the yes command outputs 'y' or whatever is specified as an argument, followed by a newline repeatedly until stopped by the user or otherwise killed; when piped into a command, it will continue until the pipe breaks (i.e., the program completes its execution).
The following C code examples illustrate two threads that share a global integer i. The first thread uses busy-waiting to check for a change in the value of i : #include <pthread.h> #include <stdatomic.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> /* i is global, so it is visible to all functions.
I/O completion port loops run separately from the Message loop, and do not interact with the Message loop out of the box. The "heart" of most Win32 applications is the WinMain() function, which calls GetMessage() in a loop. GetMessage() blocks until a message, or "event", is received (with function PeekMessage() as a non
The code "inside" the loop (the body of the loop, shown below as xxx) is obeyed a specified number of times, or once for each of a collection of items, or until some condition is met, or indefinitely. When one of those items is itself also a loop, it is called a "nested loop". [4] [5] [6]
first checks whether x is less than 5, which it is, so then the {loop body} is entered, where the printf function is run and x is incremented by 1. After completing all the statements in the loop body, the condition, (x < 5), is checked again, and the loop is executed again, this process repeating until the variable x has the value 5.
An important aspect of this, setting Unix pipes apart from other pipe implementations, is the concept of buffering: for example a sending program may produce 5000 bytes per second, and a receiving program may only be able to accept 100 bytes per second, but no data is lost. Instead, the output of the sending program is held in the buffer.
In this manner, the do ... while loop saves the initial "loop priming" with do_work(); on the line before the while loop.. As long as the continue statement is not used, the above is technically equivalent to the following (though these examples are not typical or modern style used in everyday computers):