Days ago a mate asked me a favor in his code and I got trouble in dynamic pointer and dynamic memory allocation.
\nWell, one-dimensional pointer is easy to use, and you can easily expand it’s occupied memory size by using realloc() as following:<\/p>\n
\n#include <iostream>\nusing namespace std;\nint n=2,* pint;\nvoid Initialization()\n{\n\tpint=new int[n];\n}\nvoid DoSomething(){}\nint main()\n{\n\tInitialization();\n\tDoSomething();\n\tpint=(int*)realloc(pint,(++n)*sizeof(int));\n\tpint[n-1]=123456;\n\tcout<<pint[n-1]<<endl;\n\treturn 0;\n}\n<\/pre>\nBut when it comes to the two-dimensional pointer, it nolonger works if you write some code like this:\n<pre lang="cpp" line="1" file="code2.cpp" colla="+">\n#include <iostream>\nusing namespace std;\nint n=2,len=20;\nchar** ppchar;\nvoid Initialization(){\n\tppchar=new char*[n];\n\tfor(int i=0;i<n;i++){\n\t\tppchar[i]=new char[len];\n\t}\n}\nvoid DoSomething(){}\nint main()\n{\n\tInitialization();\n\tDoSomething();\n\tppchar=(char**)realloc(ppchar,(++n)*len*sizeof(char));\n\tppchar[n-1]="this is a new one";\n\tcout<<ppchar[n-1]<<endl;\n\treturn 0;\n}\n<\/pre>\nThat is because you failed to notify the system, or in other words declare the address of ppchar[n-1].
\nAnd here is a correct version of the same function by adding a statement between line 16 and 17:<\/p>\n
\nppchar[n-1]=new char[len];\n<\/pre>\n","protected":false},"excerpt":{"rendered":"Days ago a mate asked me a favor in his code and I got trouble in dynamic pointer and dynamic memory allocation. Well, one-dimensional pointer is easy to use, and you can easily expand it’s occupied memory size by using realloc() as following: #include <iostream> using namespace std; int n=2,* pint; void Initialization() { pint=new … <\/p>\n