![]() return 0 if the string does not represent an integer, which is indistinguishable from a correctly formatted, zero-denoting input string.have undefined behavior if the value of the result cannot be represented.Specifically, the atoi(), atol(), and atoll() functions Unfortunately, atoi() and related functions lack a mechanism for reporting errors for invalid values. I'm a bit concerned that we are too heavy handed on using scanf to parse integers from strings. The ato*() or scanf() family receives input that is not a number when trying to parse one.Undefined behavior arising from using a function outside of the ato*() or scanf() family.Undefined behavior arising from a non-representable numeric value being parsed by an ato*() or scanf() function.atoi(), atol(), atoll(), atof(), The scanf()family.Invocation of dangerous functions besides the following:.CWE-676 = Union( ERR34-C, list) where list =.ERR34-C implies that string-parsing functions (eg atoi() and scanf()) are dangerous.Failure to errors outside of string-to-number conversion functions.String-to-integer conversion (ERR34-C) may qualify as input validation, but this is outside the scope of the CERT rule. Key here for mapping notes CWE-20 and ERR34-CĬERT C does not define the concept of ‘input validation’. Prior to : CERT: Unspecified RelationshipĬWE-676, Use of potentially dangerous function Use strtol() or a related function to convert a string token to an integer ![]() This noncompliant code example converts the string token stored in the buff to a signed integer value using the atoi() function: Likewise, use the strtoul() function to convert to a smaller unsigned integer type such as unsigned int, unsigned short, and unsigned char, and test the result against the range limits for that type. These range tests do nothing if the smaller type happens to have the same size and representation for a particular implementation. Also, use the strtol() function to convert to a smaller signed integer type such as signed int, signed short, and signed char, testing the result against the range limits for that type. These functions provide more robust error handling than alternative solutions. Use one of the C Standard Library strto*() functions to parse an integer or floating-point number from a string. ![]() The strtol(), strtoll(), strtoimax(), strtoul(), strtoull(), strtoumax(), strtof(), strtod(), and strtold() functions convert the initial portion of a null-terminated byte string to a long int, long long int, intmax_t, unsigned long int, unsigned long long int, uintmax_t, float, double, and long double representation, respectively. These error conditions must be detected and addressed when a string-to-number conversion is performed using a C Standard Library function. ![]() The string may also contain extra information after the number, which may or may not be useful after the conversion. It might contain a number of the correct type that is out of range (such as an integer that is larger than INT_MAX). ![]() * Indicates if the operation succeeded, or why it failed.The process of parsing an integer or floating-point number from a string can produce many errors. * - any trailing characters that are not part of the number * except that the following are inconvertible:
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