C++ : Things you might know or :?

Some of us have already studied C++ language but being in a computer stream demands from you to stand out from those who know only the text or the ordinary used commands or basic knowledge.

Here are some.... which some/all of you might know... but a quick revision or something new for you...

1. REFERNCE

An alternate name for an object in C++. It provides an alias name for previously defined variables(s).

SYNTAX:            type &ref-name=var-name;

EXAMPLE:        int total;

                              int &sum=total;

                              total=100;

                              cout<<sum<<"  "<<total;

OUTPUT:          100  100

2. SETPRECISION MANIPULATOR using IOS flag

It is used to set number of decimal places using ios flag.

EXAMPLE:         cout.setf(ios::fixed);

                               cout<<setprecision(5)<<12.345678;

OUTPUT:            12.34567           (No Rounding Off)

                          

Additional ios flags:

left                : displays left justified output

right             : displays right justified output

showpoint : displays decimal and trailing zeros even if decimal places are not needed

uppercase : displays the "e" in E-notation as "E"

showpos    : displays a leading plus(+) before the value

scientific   : displays floating point numbers in scientific ("E") notation

fixed           : displays floating point numbers in normal notation ,i.e, no trailing zeros and no scientific
                        notaions.

3. SIZEOF Operator

 Sizeof is a unary compile-time operator that returns length (in bytes) of the variable or parenthesized type-specifier that it precedes.
It can be used as:
                  sizeof var; (where var is a declared datatype)
                  sizeof (type) (where type is a C++ data type)

4. COMMA Operator

Comma operator is used to string together several expressions. The group of expressions separated by comma (,) is evaluated left-to-right in sequence and the result of rightmost expression becomes the value of the total comma-separated expression.

EXAMPLE: b=(a=3,a+1);

first assigns a the value 3 and then assigns b the value a+1 i.e., 4. The parenthesis are necessary because the comma operator has lower precedence than the assignment operator. 

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