h6. [[OS SWI Calls]] h6(. » OS_EvaluateExpression h2. OS_EvaluateExpression h5. (SWI &2D) |_<^{width:3em}. Entry | | |<^. R0 |<^. Pointer to string | |<^. R1 |<^. Pointer to buffer | |<^. R2 |<^. Length of buffer | |_<^{width:3em}. Exit | | |<^. R0 |<^. Preserved | |<^. R1 |<^. 0 if integer returned, else preserved | |<^. R2 |<^. Integer if R1=0, else length of string | h4. Use The purpose of this call is to evaluate a string and return the value into a given buffer as either a string or integer. h4. Notes This SWI takes a string, evaluates it, and places result in given buffer. Type of the result is given in R1 : |<^{width:3em}. 0|<^. Integer returned in R2| |<^. Not 0|<^. Pointer to string, length in R2| For a comprehensive list of expressions that can be used with this SWI please see the [[Expressions|Expressions]] page. Floating point numbers cannot be used within expressions.