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Typically, converting an integer to a smaller type results in truncation of the high-order btis.
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Non-Compliant Code Example
Type range errors, including loss of data (truncation) and loss of sign (sign errors), can occur when converting from an unsigned type to a signed type. The following code is likely to result in a truncation error for almost all implementations:
| Code Block |
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unsigned long int ul = ULONG_MAX;
signed char sc;
sc = (signed char)ul; /* cast eliminates warning */
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Compliant Solution
Validate ranges when converting from an unsigned type to a signed type. The following code, for example, can be used when converting from unsigned long int to a signed char.
| Code Block |
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unsigned long int ul = ULONG_MAX;
signed char sc;
if (ul <= SCHAR_MAX) {
sc = (signed char)ul; /* use cast to eliminate warning */
}
else {
/* handle error condition */
}
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Non-Compliant Code Example
Type range errors, including loss of data (truncation) and loss of sign (sign errors), can occur when converting from a signed type to an unsigned type. The following code results in a loss of sign:
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NOTE: While unsigned types can usually represent all positive values of the corresponding signed type, this relationship is not guaranteed by the C99 standard.
Non-Compliant Code Example
A loss of data (truncation) can occur when converting from a signed type to a signed type with less precision. The following code is likely to result in a truncation error for most implementations:
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Conversions from signed types with greater precision to signed types with lesser precision require both the upper and lower bounds to be checked.
Non-Compliant Code Example
A loss of data (truncation) can occur when converting from an unsigned type to an unsigned type with less precision. The following code is likely to result in a truncation error for most implementations:
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