Tokens in C with example

 In C programming, a token is the smallest individual unit in the source code that the compiler can understand. Tokens are building blocks of C programs and are used to form expressions, statements, and other elements in the code. C tokens are of various types, such as keywords, identifiers, constants, strings, operators, and punctuators. Let's explore each type of token with examples:

1. Keywords:
Keywords are reserved words in the C language that have a specific meaning and cannot be used as variable names. Examples of C keywords include `int`, `float`, `if`, `else`, `for`, `while`, etc.

```c
#include <stdio.h>

int main() {
    int num = 10;  // 'int', 'main', 'return' are keywords
    if (num > 0) {
        printf("Positive number\n");  // 'if', 'printf' are keywords
    }
    return 0;  // 'return' is a keyword
}
```

2. Identifiers:
Identifiers are names used to identify variables, functions, or any other user-defined entity in the code. An identifier must start with a letter or an underscore and can be followed by letters, digits, or underscores.

```c
#include <stdio.h>

int main() {
    int x;  // 'x' is an identifier (variable name)
    float average;  // 'average' is an identifier (variable name)
    
    return 0;
}
```

3. Constants:
Constants are fixed values that do not change during the program's execution. There are two types of constants in C: integer constants and floating-point constants.

```c
#include <stdio.h>

int main() {
    int num = 42;  // '42' is an integer constant
    float pi = 3.14;  // '3.14' is a floating-point constant

    return 0;
}
```

4. Strings:
Strings are sequences of characters enclosed in double quotes. They are used to represent textual data.

```c
#include <stdio.h>

int main() {
    char greeting[] = "Hello, World!";  // "Hello, World!" is a string

    printf("%s\n", greeting);

    return 0;
}
```

5. Operators:
Operators are symbols used to perform operations on operands. C provides various types of operators, such as arithmetic, relational, logical, assignment, etc.

```c
#include <stdio.h>

int main() {
    int a = 5, b = 3;  // '=' and ',' are operators
    int sum = a + b;  // '+' is an operator

    if (a > b) {  // '>' is an operator
        printf("a is greater than b\n");
    }

    return 0;
}
```

6. Punctuators:
Punctuators are symbols that are used as separators or terminators in C code.

```c
#include <stdio.h>

int main() {
    int x = 10;  // '=' and ';' are punctuators

    for (int i = 0; i < 5; i++) {  // '(', ')', '{', '}', ';', '<', '++' are punctuators
        printf("%d ", i);
    }

    return 0;
}
```

These are the main types of tokens in C programming. Understanding and identifying these tokens is crucial for writing correct and error-free C code.