---
title: 1.24 Basic Type Qualifiers
description: "Type qualifiers modify how an object can be accessed or used. The three standard C type qualifiers are `const`, `volatile`, and `restrict`. ``` #include int main() { const int maximum = 100; volatile int status = 0; printf(\"%d\\n\", maximum); printf(\"%d\\n\",…"
url: "https://edcret.in/docs/c-programming/basic-refreshers/1-24-basic-type-qualifiers/"
updated: "2026-09-06"
category: C Programming / Basic Refreshers
---

# 1.24 Basic Type Qualifiers

Type qualifiers modify how an object can be accessed or used. The three standard C type qualifiers are `const`, `volatile`, and `restrict`.

```
#include <stdio.h>

int main()
{
    const int maximum = 100;
    volatile int status = 0;

    printf("%d\n", maximum);
    printf("%d\n", status);

    return 0;
}
```

### Example Output

```
100
0
```

### Explanation

`const` indicates that an object cannot be modified through the qualified lvalue:

```
const int maximum = 100;
```

An assignment such as:

```
maximum = 200;
```

is not allowed.

`volatile` indicates that accesses to an object may have observable effects outside the normal flow assumed by the compiler:

```
volatile int status = 0;
```

It is commonly used for objects that can change because of hardware or other execution contexts.

`restrict` is a qualifier used with pointers. It provides an optimization-related aliasing guarantee when the pointer is used according to the requirements of the qualifier.

```
int * restrict ptr;
```

### Type Qualifiers

| Qualifier | Purpose |
| --- | --- |
| `const` | Prevents modification through the qualified access |
| `volatile` | Indicates that accesses to the object must be treated as potentially externally observable |
| `restrict` | Provides a restricted pointer-aliasing contract |
| `_Atomic` | Specifies atomic types or atomic-qualified access in C11 and later |

The qualifiers can also be combined:

```
const volatile int status;
```

Here, `status` is both `const` and `volatile`.