Usage of scanf_s in c language

scanf_s is a safe function in C language to read formatted data to prevent buffer overflow attacks. Its syntax is: scanf_s(format, ...). Usage steps: Include the header file stdio.h. Prepend the & symbol before the variable. Make sure the format specifier matches the data type. Check the return value to detect errors.

Usage of scanf_s in C language

The scanf_s function is used in C language to read format from standard input A secure version of your data. Unlike the unsafe scanf function, scanf_s validates input and protects against buffer overflow attacks.

Syntax

<code class="c">int scanf_s(const char *format, ...);</code>

Parameters

• format: A format specifier string , specifying the data type to be read.
• ...: A variable argument list providing the address of the data to be read.

Return value

scanf_s Returns the number of items that have been successfully read. Returns -1 if the input is malformed or an error is encountered.

Usage

To use scanf_s, follow these steps:

1. Include the stdio.h header file .
2. Place the & symbol before the variable from which data is to be read.
3. Make sure the format specifier matches the data type being read.
4. Check the return value of scanf_s to detect errors.

Example

<code class="c">#include <stdio.h>

int main()
{
    int age;
    char name[20];

    printf("输入你的年龄：");
    if (scanf_s("%d", &age) != 1)
    {
        printf("输入无效！\n");
        return 1;
    }

    printf("输入你的姓名：");
    if (scanf_s("%s", name, sizeof(name)) != 1)
    {
        printf("输入无效！\n");
        return 1;
    }

    printf("你好，%s！你的年龄是 %d。\n", name, age);

    return 0;
}</code>

Notes

• scanf_s is a safe version and scanf will not appear Buffer overflow problem in .
• scanf_s returns the number of items successfully read, not the number of matching items like scanf.
• To scan a string, use the %s format specifier and specify the maximum length of the string.
• scanf_s does not support the %n format specifier.

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