Division and modulo operations are susceptible to divide-by-zero errors. According to the C Standard, Section 6.5.5, paragraph 5 [ISO/IEC 9899:2011],
The result of the
/operator is the quotient from the division of the first operand by the second; the result of the%operator is the remainder. In both operations, if the value of the second operand is zero, the behavior is undefined.
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C identifies two conditions under which division and modulo operations result in undefined behavior:
| UB | Description |
The value of the second operand of the | |
| n/a | If the quotient a/b is not representable, the behavior of both a/b and a%b is undefined (6.5.5). |
Division
The result of the / operator is the quotient from the division of the first arithmetic operand by the second arithmetic operand. Division operations are susceptible to divide-by-zero errors. Overflow can also occur during two's complement signed integer division when the dividend is equal to the minimum (negative) value for the signed integer type and the divisor is equal to −1. (See INT32-C. Ensure that operations on signed integers do not result in overflow.)
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| CERT C++ Secure Coding Standard | INT33-CPP. Ensure that division and modulo operations do not result in divide-by-zero errors |
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| CERT Oracle Secure Coding Standard for Java | NUM02-J. Ensure that division and modulo operations do not result in divide-by-zero errors |
| ISO/IEC TS 17961 | (Draft) Dividing by zero [divzero] |
| ISO/IEC TS 17961 | (Draft) Integer division errors [diverr] |
| MITRE CWE | CWE-369, Divide by zero |
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| [Seacord 2005] | Chapter 5, "Integers" |
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| [Warren 2002] | Chapter 2, "Basics" |