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Alternative functions that limit the number of bytes copied are often recommended to mitigate buffer overflow vulnerabilities, for example:

• strncpy() instead of strcpy()
• fgets() instead of gets()
• snprintf() instead of sprintf()

These function truncate strings that exceed the specified limits. Additionally, some functions such as strncpy() do not guarantee that the resulting string is null-terminated .
Truncation results in a loss of data, and in some cases, leads to software vulnerabilities.

Non-Compliant Code Example

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These two lines of code assume that gets() will not read more than BUFSIZ characters from stdin.  This is an invalid assumption and the resulting operation can result in a buffer overflow.

Code Block
char buf[BUFSIZ + 1]; gets(buf);

Non-Compliant Code Example

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The standard function strncpy() and strncat() do not guarantee that the resulting string is null terminated.  If there is no null character in the first n characters of the source array pointed the result is not be null-terminated as in the following example:

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