Learn C Programming
realloc() We may need to resize the dynamically allocated memory in our C-program. Resizing can be done to increase as well as decrease the size of dynamically added memory. realloc is the system call that enables us to do the same. Let us begin with understanding the syntax for the same void* realloc (void* ptr,…
Continue ReadingWhat is binary file? Binary files store data in binary format, and not in plain text format. A binary file is computer readable and not human readable. We can assume them to be similar to arrays of structures, except the structures are in a disk file rather than in an array in memory. Unlike plain…
Continue ReadingBefore we get to understand epsilon, let us first understand what is precision of a number? What is precision? As we have explained in detail in “The book of C”, each data type has a finite memory allocated to it and hence it can store finite range of data. In case of floating point numbers…
Continue ReadingWhat is environment variable? As the name suggests, environment variables are are part of the environment in which a process executes. e.g. if we run a command ‘ls‘ on command prompt on a Linux terminal, the Terminal is the environment in which the ls is executed, and environment variables are part of the terminal. PATH…
Continue ReadingWhat is preprocessing? Preprocessing, as the name suggests, is the preprocessing of C-code before the actual compilation begins. In C, a line that begins with ‘#’ character is called a preprocessing directive. It is an indicator to the compiler that this preprocessing directive needs to be processed before compilation phase begins. Preprocessing directives Source file…
Continue ReadingWe learned how to launch a program from command line [Refer: https://www.thebookofc.com/environment/launching-from-command-line/]. But how do we check the return value of a program executed on command line? How to check return value on Linux? To know the return value of a program executed from the command line, all we need to do is type the…
Continue ReadingWe know that in a C-program the function main can take two arguments, signature being, int main(int argc, char** argv) How do we pass these arguments to main? One way is to launch the program via command line. Let us understand it step by step with an example. We take the sample example from our…
Continue ReadingSigned numbers in digital world In real world, it is easy to represent negative numbers as we can prefix a ‘+’ or ‘–’ sign to the number to denote if it is a positive or negative number. However, in digital world, we need to store all numbers as ‘0’ or ‘1’ and hence we need…
Continue ReadingWhat is overflow? Overflow is a situation when an arithmetic operation results in a value that is too large to be stored in the specified datatype. Let’s consider the following example: int a = 2147483647; a++; printf (“value of a is %d\n”, a); The range for an int datatype (assuming its size to be 4…
Continue ReadingAs discussed in the book, each data type has a finite size. There is a the minimum range of values each data type supports as required by the C standard. However, the compiler implementations may vary and hence, may have a larger range actually supported. C provides the programmers with pre-defined macros to find out…
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