In C, the **`atoi()` function** converts a string to an integer.

## Syntax
The syntax for the function is given below: 


### Parameters
The function takes as input the string that is to be converted to an integer. 

### Return value
1. If successfully executed, the function returns the integer value.
2.  If the string starts with an alphanumeric character or only contains alphanumeric characters, 0 is returned.

3. In case the string starts with a numeric character but is followed by an alpha-numeric character, the string is converted to an integer until the occurrence of the first alphanumeric character

> **Note:**
The `stdlib.h` library must be included for the `atoi()` function to be executed
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## Example
Let's look at an example to further understand the working of the `atoi()` function:

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

int main() {
    // Converting a numeric string
    char str[10] = "122";
    int x = atoi(str);
    printf("Converting '122': %d\n", x);

    // Converting an alphanumeric string
    char str2[10] = "Hello!";
    x = atoi(str2);
    printf("Converting 'Hello!': %d\n", x);

    // Converting a partial string
    char str3[10] = "99Hello!";
    x = atoi(str3);
    printf("Converting '99Hello!': %d\n", x);
    return 0;
}

How to convert a string to an integer in C

Syntax

Parameters

Return value

Example