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POconst char* variable as parameter to function
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  1. POconst char* variable as parameter to function
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    copied!<p>I have this constructor implemented in a C++ library(by someone else, not by me):</p> <pre><code>Variables(const char *s) </code></pre> <p>Which I want to use in my own function, useful(). This functions useful(), computes an int which I want to be transmitted as a parameter to the constructor Variables(const char *s).</p> <p>So I am converting the int to a string and then to a const char* data type. And them I am transmitted it as a parameter to the Variables constructor, but I get an error message.</p> <p>Depending on the integers in the variable loopOE, I am constructing a string "xi", where i is the ith integer from the vector loopOE. For example is loops[0]=2, then we create the string "x2", which is then converted to a <code>const char *</code>, and then transmitted to the constructor Variables(const char* s).</p> <p>My function useful() looks in the following way:</p> <pre><code>void useful(){ vector&lt;int&gt; loopsOE; for (unsigned int i=0;i&lt;6;i++) loopsOE.push_back(i); for (unsigned int i=0;i&lt;loopsOE.size();i++){ //convering int to string std :: ostringstream sstreamComplete; sstreamComplete &lt;&lt; loopsOE[i]; std :: string loopsOEStr=sstreamComplete.str(); //construct the string variable "xi" string varPoly("x"); varPoly.append(loopsOEStr); //converting the string to char* const char* varPolyConverted=varPoly.c_str() } std::vector&lt; polynomial_t &gt; Vec(myEdgesIntersect.size()); Variables V(varPolyConverted); } </code></pre> <p>When I try to compile this function I get the following error message:</p> <blockquote> <p>QSweepComplete.cpp: In member function 'void QSweepComplete::prealexMatrix()': QSweepComplete.cpp:975: error: 'varPolyConverted' was not declared in this scope make: *** [.obj/QSweepComplete.o] Error 1</p> </blockquote> <p>Still I don't understand as if I modify the function with a simple constant in the following way:</p> <pre><code>void usefulModified(){ vector&lt;int&gt; loopsOE; for (unsigned int i=0;i&lt;6;i++) loopsOE.push_back(i); for (unsigned int i=0;i&lt;loopsOE.size();i++){ //convering int to string std :: ostringstream sstreamComplete; sstreamComplete &lt;&lt; loopsOE[i]; std :: string loopsOEStr=sstreamComplete.str(); //construct the string variable "xi" string varPoly("x"); varPoly.append(loopsOEStr); //converting the string to char* const char* varPolyConverted=varPoly.c_str() } std::vector&lt; polynomial_t &gt; Vec(myEdgesIntersect.size()); const char * str="x0"; Variables V(str); } </code></pre> <p>the function compiles and runs without any problems.</p> <p>If anyone has any suggestions, I will strongly appreciate them.</p> <p>Thanks in advance. Best wishes, madalina</p>
 

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