Practical C Programming - Chapter 4

Chapter 4. Basic Declarations and Expressions

Basic Program Structure

The function named main is special, because it is the first function called. Other functions are called directly or indirectly from main.

int main(){  return (0);}

The line return (0); is used to tell the operating system that the program exited normally(Status=0). A nonzero status indicates an error — the bigger the return value, the more severe the error.

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The statement #include <stdio.h> signals C that we are going to use the standard I/O package. Technically, this statement causes a set of data declarations to be taken from an include file.

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Variable name starts with a letter or underscore(_), followed by any number of letters, digits, or underscores. Uppercase is different from lowercase.

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5 // int5.0 // floating-point5.  // floating-point0.5 // floating-point.5  // floating-point0.0 // floating-point zero1.2e3 // exponent specification 1.2*10^34

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The backslash character () is called the escape character. It is used to signal that a special character follows.

Character Name Meaning \b Backspace Move the cursor to the left by one character \f Form Feed Go to top of new page \n Newline Go to next line \r Return Go to beginning of current line \t Tab Advance to next tab stop \’ Apostrophe Character ‘ \” Double quote Character “ \ Backslash Character \ \nnn Character number nnn (octal)