Data Types In C

In C datatypes are a large set of rules for declaring variables and functions of different types. A variable’s type tells you how much space it takes up in storage and how to read the bit pattern it stores.

The types in C can be put into the following groups:

The aggregate types are made up of the array types and the structure types. The type of a function tells you what kind of value it returns. The next section will talk about the basic types. The next chapters will talk about the other types

Integer Types

The standard integer types, their storage sizes, and the value ranges they support are shown in the table below.

On a certain platform, you can use thesizeof operator to find out the exact size of a type or variable. When you type sizeof(type), you get the object or type’s storage size in bytes. Here is an example of how to use different constants set in limits to get the size of different types on a machine. h file header.

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <float.h>

int main(int argc, char** argv) {

    printf("CHAR_BIT    :   %d\n", CHAR_BIT);
    printf("CHAR_MAX    :   %d\n", CHAR_MAX);
    printf("CHAR_MIN    :   %d\n", CHAR_MIN);
    printf("INT_MAX     :   %d\n", INT_MAX);
    printf("INT_MIN     :   %d\n", INT_MIN);
    printf("LONG_MAX    :   %ld\n", (long) LONG_MAX);
    printf("LONG_MIN    :   %ld\n", (long) LONG_MIN);
    printf("SCHAR_MAX   :   %d\n", SCHAR_MAX);
    printf("SCHAR_MIN   :   %d\n", SCHAR_MIN);
    printf("SHRT_MAX    :   %d\n", SHRT_MAX);
    printf("SHRT_MIN    :   %d\n", SHRT_MIN);
    printf("UCHAR_MAX   :   %d\n", UCHAR_MAX);
    printf("UINT_MAX    :   %u\n", (unsigned int) UINT_MAX);
    printf("ULONG_MAX   :   %lu\n", (unsigned long) ULONG_MAX);
    printf("USHRT_MAX   :   %d\n", (unsigned short) USHRT_MAX);

    return 0;
}

When you compile and run the above program on Linux, it gives you the following output:

CHAR_BIT    :   8
CHAR_MAX    :   127
CHAR_MIN    :   -128
INT_MAX     :   2147483647
INT_MIN     :   -2147483648
LONG_MAX    :   2147483647
LONG_MIN    :   -2147483648
SCHAR_MAX   :   127
SCHAR_MIN   :   -128
SHRT_MAX    :   32767
SHRT_MIN    :   -32768
UCHAR_MAX   :   255
UINT_MAX    :   4294967295
ULONG_MAX   :   4294967295
USHRT_MAX   :   65535

Floating-Point Types

The table below shows the standard floating-point types, along with their precision, storage sizes, and value ranges.

The header file float.h sets up macros that let you use these numbers and other information about how real numbers are represented in binary in your programs. The next code shows how much space a float type and its range values take up.

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <float.h>

int main(int argc, char** argv) {

    printf("Storage size for float : %d \n", sizeof(float));
    printf("FLT_MAX     :   %g\n", (float) FLT_MAX);
    printf("FLT_MIN     :   %g\n", (float) FLT_MIN);
    printf("-FLT_MAX    :   %g\n", (float) -FLT_MAX);
    printf("-FLT_MIN    :   %g\n", (float) -FLT_MIN);
    printf("DBL_MAX     :   %g\n", (double) DBL_MAX);
    printf("DBL_MIN     :   %g\n", (double) DBL_MIN);
    printf("-DBL_MAX     :  %g\n", (double) -DBL_MAX);
    printf("Precision value: %d\n", FLT_DIG );

    return 0;
}

When you compile and run the above program on Linux, it gives you the following output:

Storage size for float : 4
FLT_MAX     :   3.40282e+038
FLT_MIN     :   1.17549e-038
-FLT_MAX    :   -3.40282e+038
-FLT_MIN    :   -1.17549e-038
DBL_MAX     :   1.79769e+308
DBL_MIN     :   2.22507e-308
-DBL_MAX     :  -1.79769e+308
Precision value: 6

The void Type

The void type means that there is no value. You can use it in three different ways: