The role of scanf_s in c language

The function of scanf_s is to read formatted data from the standard input stream into variables. Perform range checks to prevent buffer overflows. Detect format string vulnerabilities and prevent application vulnerabilities.

The role of scanf_s function in C language

The scanf_s function is a safe input function in the C language standard library , used to read formatted data from the standard input stream. It is similar to the scanf function, but adds additional security checks to prevent buffer overflows and format string vulnerabilities.

Function

The main function of scanf_s function is:

• Read formatted data from the standard input stream and store it in in the specified variable.
• Perform range checking to ensure that the input data does not exceed the scope of the variable.
• Detect format string vulnerabilities to prevent applications from crashing or being exploited by attackers.

Usage

The syntax of the scanf_s function is as follows:

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

Among them:

• format is a format string specifying the format of the input data.
• ... is a variadic argument list containing the addresses to be stored in variables.

Example

The following example demonstrates the use of the scanf_s function:

<code class="c">int age;
if (scanf_s("Enter your age: %d", &age) == 1) {
    printf("Your age is %d.\n", age);
} else {
    printf("Invalid input.\n");
}</code>

In this example:

# The ##scanf_s function reads an integer (using the %d format specifier) ​​and stores it in the age variable.
• If the input is valid (that is, an integer was entered), print the value of the age variable.
• Otherwise, print an error message.

Differences from scanf

The main difference between the scanf_s function and the scanf function is that it is safe. The scanf function can allow buffer overflows and format string vulnerabilities, while the scanf_s function prevents these problems by performing additional security checks.

Conclusion

The scanf_s function is a safe version of the scanf function that can be used to read formatted data from the standard input stream. It performs range checking and format string vulnerability detection to prevent buffer overflows and attacks.

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