SW500010 Microchip Technology, SW500010 Datasheet - Page 429

• Manufacturer Part Number: SW500010
• Description: HI-TECH C PRO FOR PIC10/12/16
• Manufacturer: Microchip Technology
• Type: Compilerr
• Series: PIC10/12/16r

Specifications of SW500010

• Supported Families: PIC10, PIC12, PIC16
• Core Architecture: PIC
• Software Edition: Professional
• Kit Contents: Software And Docs
• Mcu Supported Families: PIC10/12/16
• Tool Type: Compiler
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• For Use With/related Products: PIC10, PIC12, PIC14, PIC16, PIC16E
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 019P; 778-1006; 778-1006

Error and Warning Messages
(751) arithmetic overflow in constant expression
A constant expression has been evaluated by the code generator that has resulted in a value that is
too big for the type of the expression. The most common code to trigger this warning is assignments
to signed data types. For example:
As a signed 8-bit quantity, c can only be assigned values -128 to 127. The constant is equal to
255 and is outside this range. If you mean to set all bits in this variable, then use either of:
which will set all the bits in the variable regardless of the size of the variable and without warning.
A quick check with your calculator reveals that 240 * 137 is 32880 which can easily be stored in
an unsigned int, but a warning is produced. Why? Because 240 and 137 and both signed
int values. Therefore the result of the multiplication must also be a signed int value, but
a signed int cannot hold the value 32880. (Both operands are constant values so the code
generator can evaluate this expression at compile time, but it must do so following all the ANSI
rules.) The following code forces the multiplication to be performed with an unsigned result:
(752) conversion to shorter data type
Truncation may occur in this expression as the lvalue is of shorter type than the rvalue, e.g.:
This warning can also be triggered by intermediate values overflowing. For example:
signed char c;
c = 0xFF;
c = ~0x0;
c = -1;
unsigned int i;
i = 240 * 137;
i = 240u * 137;
char a;
int b, c;
a = b + c;
/ * int to char conversion
may result in truncation * /
/ * assume ints are 16 bits wide * /
/ * this should be okay, right? * /
/ * force at least one operand
to be unsigned * /
(Code Generator)
(Code Generator)
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