how to use a strut variable in c code example

Example 1: declare variable in c

int    i, j, k;
char   c, ch;
float  f, salary;
double d;

Example 2: c how to define a variable

int age;			//int variableName; or int variableName = Value;
			//Integers are whole numbers: 2, 23. They are NOT: 28.4, 8.07.
char first_initial;	//char variableName; or char variableName = 'Character';
			//Characters are single characters on the keyboard. Numbers can 
            //be characters but they are best not stored as such
char name[10]; 		//char stringName[size] or char stringName[size] = "String"
			//Strings are defined as an array of characters that end
            //w/a special character ‘\0’.
float salary;		//float variableName; or float variableName = value;
			//Floats are numbers that contain up to seven digits including decimals.
double micro;		//double variableName; or double variableName = value;
			//Doubles are more precise than floats and can hold more numbers.