Chapter 10, Problem 6RQE

Explanation of Solution

“cstdlib” header file:

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The C++ library contains many functions for string/numeric conversions; The “cstdlib” header file must be used for converting C-string and string value to numeric data type and vice versa.

The “atoi” and “atof” functions must need “cstdlib” header file for converting string to numeric data type.

• atoi – it converts C-string argument to integer value.
• atof – it converts C-string argument to double value.

“atoi” function:

In C++, the predefined function “atoi” is used to convert a string value into an integer value; it passes a string literal or character array as an argument and it converts the received value into an integer value; it takes only one parameter as an argument.

• If the argument value contains nonconvertible contents combined with the integer value then the values will be ignored while converting.
• In same way, the function will return “0” when the values can’t be able to convert into double data type.

Syntax:

The syntax for the “atoi” function is as follows:

int atoi (const char* n);

In the above statement,

• “int” represents the return type of the function.
• “atoi” represents the name of the function.
• “const char*” represents the data type of the passing argument.
• “n” is a string variable which is required to be converted.

Example:

The example for the “atoi” function is as follows:

//change the string literal to an int value

int n = atoi("123456 hai");

In the above line, the string literal “123456 hai” is passed as an argument to “atoi” and it returns the converted value that is “123456”; here the “atoi” function ignores the whitespace and the nonconvertible value “hai”...