| Topic: |
DEVELOP > c-Plus-Plus |
| User: |
"stanlo" |
| Date: |
09 Jan 2005 03:57:01 PM |
| Object: |
alternative for pointers |
Hello to all, i have a progam fragment here for the follow up of my
project ; mathematicl expression. i don t want to use pointers, this is
the fragment.my problem is there an alternative way of declaring and
defining my functions without using pointers,eg in the goToOp1
function, i don t wish to write "char*line".
this function gets the first operator in the mathematical expression
like 1+6*6/2.
//function declarations
int goToOp1(char* line, int startPos, int &curExprBegin);
int goToOp2(char* line, int startPos, int &curExprEnd);
void reduceArr(char* line, int curExprBegin, int curExprEnd, long
number);
void discardBadChar(char* line, bool &exit);
void errorOutput(const char* erroralert);
//function definitons, i did just the definition of one of the
functions
int goToOp1(char* line, int startPos, int &curExprBegin)
{
int pos=startPos-2;
int op1Size=0;
int answer;
answer = 0;
.
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| User: "Mike Wahler" |
|
| Title: Re: alternative for pointers |
09 Jan 2005 04:25:29 PM |
|
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"stanlo" <mungwest@yahoo.com> wrote in message
news:1105307821.732625.54300@c13g2000cwb.googlegroups.com...
Hello to all, i have a progam fragment here for the follow up of my
project ; mathematicl expression. i don t want to use pointers, this is
the fragment.my problem is there an alternative way of declaring and
defining my functions without using pointers,eg in the goToOp1
function, i don t wish to write "char*line".
If you insist upon using 'C-style' strings, pointers are
the only way to pass them to functions. However the C++
standard library provides a 'string' type (declared by standard
header <string>). Look it up in your C++ textbook.
this function gets the first operator in the mathematical expression
like 1+6*6/2.
//function declarations
int goToOp1(char* line, int startPos, int &curExprBegin);
int goToOp1(const std::string& line,
std::string::size_type startPos,
int &curExprBegin);
int goToOp2(char* line, int startPos, int &curExprEnd);
int goToOp2(const std::string& line,
std::string::size_type startPos,
int &curExprEnd);
void reduceArr(char* line, int curExprBegin, int curExprEnd, long
number);
void reduceArr(const std::string& line,
int curExprBegin,
int curExprEnd,
long number);
BTW why do some of these take references to int, and some
int by value?
void discardBadChar(char* line, bool &exit);
void discardBadChar(const std::string& line, bool &exit);
void errorOutput(const char* erroralert);
void errorOutput(const std::string& erroralert);
//function definitons, i did just the definition of one of the
functions
int goToOp1(char* line, int startPos, int &curExprBegin)
int goToOp1(const std::string& line,
std::string::size_type startPos,
int &curExprBegin)
{
int pos=startPos-2;
std::string::size_type pos(startPos-2);
Why subtracting 2?
int op1Size=0;
int answer;
answer = 0;
Why not simply:
int answer(0);
Without more context, I cannot comment on whether your
other argument types and return types are appropriate.
-Mike
.
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