strncpy char string issue when deleting the array










-1















I don't know, problem with this error. However, I think I should delete uName before I delete the cpp. How can I do for this?



#define _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
#include <string.h>

using namespace std;
class cppUr

public:
void writeName(char nm);
char * readName();

private:
char uName[80];
;
void cppUr::writeName(char nm)

strncpy(uName, nm, 79);

char * cppUr::readName()

return uName;



The main is:



int main()

char name0[100];
char name1[100];
char name2[100];
char name3[100];
cppUr *cpp = new cppUr[3];
cout << "Input first name: "<<endl;
cin.getline(name0, 100);
cpp[0].writeName(name0);
cout << "Input second name: " << endl;
cin.getline(name1, 100);
cpp[1].writeName(name1);
cout << "Input third name: " << endl;
cin.getline(name2, 100);
cpp[2].writeName(name2);
cout << "Input fourth name: " << endl;
cin.getline(name3, 100);
cpp[3].writeName(name3);
for (int i = 0; i < 4; i++)

cpp[i].readName();
cout << "The "<<i<<" name " << cpp[i].readName() << endl;

delete cpp;
system("PAUSE");
return 0;



The error is:




HEAP CORRUPTION DETECTED: after Normal block(#148) at 0x0059E1E0.
CRT detected that the application wrote to memory after end of heap buffer











share|improve this question



















  • 2





    You allocate 3 cppUr but then use 4.

    – tkausl
    Nov 13 '18 at 18:06






  • 2





    And you should not ever delete uName. It is statically allocated, not dynamically. There is also no reason to dynamically allocate cpp and if you are learning C++, you should use std::string instead of all the char, char*, strncpy and manual dynamic memory management.

    – user10605163
    Nov 13 '18 at 18:11







  • 2





    This would be much simpler with std::string instead of C-style strings.

    – Pete Becker
    Nov 13 '18 at 18:19






  • 1





    Note that strncpy is not a "safe" replacement for strcpy, for any reasonable definition of "safe". Read its documentation carefully.

    – Pete Becker
    Nov 13 '18 at 18:20















-1















I don't know, problem with this error. However, I think I should delete uName before I delete the cpp. How can I do for this?



#define _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
#include <string.h>

using namespace std;
class cppUr

public:
void writeName(char nm);
char * readName();

private:
char uName[80];
;
void cppUr::writeName(char nm)

strncpy(uName, nm, 79);

char * cppUr::readName()

return uName;



The main is:



int main()

char name0[100];
char name1[100];
char name2[100];
char name3[100];
cppUr *cpp = new cppUr[3];
cout << "Input first name: "<<endl;
cin.getline(name0, 100);
cpp[0].writeName(name0);
cout << "Input second name: " << endl;
cin.getline(name1, 100);
cpp[1].writeName(name1);
cout << "Input third name: " << endl;
cin.getline(name2, 100);
cpp[2].writeName(name2);
cout << "Input fourth name: " << endl;
cin.getline(name3, 100);
cpp[3].writeName(name3);
for (int i = 0; i < 4; i++)

cpp[i].readName();
cout << "The "<<i<<" name " << cpp[i].readName() << endl;

delete cpp;
system("PAUSE");
return 0;



The error is:




HEAP CORRUPTION DETECTED: after Normal block(#148) at 0x0059E1E0.
CRT detected that the application wrote to memory after end of heap buffer











share|improve this question



















  • 2





    You allocate 3 cppUr but then use 4.

    – tkausl
    Nov 13 '18 at 18:06






  • 2





    And you should not ever delete uName. It is statically allocated, not dynamically. There is also no reason to dynamically allocate cpp and if you are learning C++, you should use std::string instead of all the char, char*, strncpy and manual dynamic memory management.

    – user10605163
    Nov 13 '18 at 18:11







  • 2





    This would be much simpler with std::string instead of C-style strings.

    – Pete Becker
    Nov 13 '18 at 18:19






  • 1





    Note that strncpy is not a "safe" replacement for strcpy, for any reasonable definition of "safe". Read its documentation carefully.

    – Pete Becker
    Nov 13 '18 at 18:20













-1












-1








-1








I don't know, problem with this error. However, I think I should delete uName before I delete the cpp. How can I do for this?



#define _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
#include <string.h>

using namespace std;
class cppUr

public:
void writeName(char nm);
char * readName();

private:
char uName[80];
;
void cppUr::writeName(char nm)

strncpy(uName, nm, 79);

char * cppUr::readName()

return uName;



The main is:



int main()

char name0[100];
char name1[100];
char name2[100];
char name3[100];
cppUr *cpp = new cppUr[3];
cout << "Input first name: "<<endl;
cin.getline(name0, 100);
cpp[0].writeName(name0);
cout << "Input second name: " << endl;
cin.getline(name1, 100);
cpp[1].writeName(name1);
cout << "Input third name: " << endl;
cin.getline(name2, 100);
cpp[2].writeName(name2);
cout << "Input fourth name: " << endl;
cin.getline(name3, 100);
cpp[3].writeName(name3);
for (int i = 0; i < 4; i++)

cpp[i].readName();
cout << "The "<<i<<" name " << cpp[i].readName() << endl;

delete cpp;
system("PAUSE");
return 0;



The error is:




HEAP CORRUPTION DETECTED: after Normal block(#148) at 0x0059E1E0.
CRT detected that the application wrote to memory after end of heap buffer











share|improve this question
















I don't know, problem with this error. However, I think I should delete uName before I delete the cpp. How can I do for this?



#define _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
#include <string.h>

using namespace std;
class cppUr

public:
void writeName(char nm);
char * readName();

private:
char uName[80];
;
void cppUr::writeName(char nm)

strncpy(uName, nm, 79);

char * cppUr::readName()

return uName;



The main is:



int main()

char name0[100];
char name1[100];
char name2[100];
char name3[100];
cppUr *cpp = new cppUr[3];
cout << "Input first name: "<<endl;
cin.getline(name0, 100);
cpp[0].writeName(name0);
cout << "Input second name: " << endl;
cin.getline(name1, 100);
cpp[1].writeName(name1);
cout << "Input third name: " << endl;
cin.getline(name2, 100);
cpp[2].writeName(name2);
cout << "Input fourth name: " << endl;
cin.getline(name3, 100);
cpp[3].writeName(name3);
for (int i = 0; i < 4; i++)

cpp[i].readName();
cout << "The "<<i<<" name " << cpp[i].readName() << endl;

delete cpp;
system("PAUSE");
return 0;



The error is:




HEAP CORRUPTION DETECTED: after Normal block(#148) at 0x0059E1E0.
CRT detected that the application wrote to memory after end of heap buffer








c++ arrays object strncpy






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 13 '18 at 20:02









Rajeev Atmakuri

6891819




6891819










asked Nov 13 '18 at 18:04









wong waimanwong waiman

81




81







  • 2





    You allocate 3 cppUr but then use 4.

    – tkausl
    Nov 13 '18 at 18:06






  • 2





    And you should not ever delete uName. It is statically allocated, not dynamically. There is also no reason to dynamically allocate cpp and if you are learning C++, you should use std::string instead of all the char, char*, strncpy and manual dynamic memory management.

    – user10605163
    Nov 13 '18 at 18:11







  • 2





    This would be much simpler with std::string instead of C-style strings.

    – Pete Becker
    Nov 13 '18 at 18:19






  • 1





    Note that strncpy is not a "safe" replacement for strcpy, for any reasonable definition of "safe". Read its documentation carefully.

    – Pete Becker
    Nov 13 '18 at 18:20












  • 2





    You allocate 3 cppUr but then use 4.

    – tkausl
    Nov 13 '18 at 18:06






  • 2





    And you should not ever delete uName. It is statically allocated, not dynamically. There is also no reason to dynamically allocate cpp and if you are learning C++, you should use std::string instead of all the char, char*, strncpy and manual dynamic memory management.

    – user10605163
    Nov 13 '18 at 18:11







  • 2





    This would be much simpler with std::string instead of C-style strings.

    – Pete Becker
    Nov 13 '18 at 18:19






  • 1





    Note that strncpy is not a "safe" replacement for strcpy, for any reasonable definition of "safe". Read its documentation carefully.

    – Pete Becker
    Nov 13 '18 at 18:20







2




2





You allocate 3 cppUr but then use 4.

– tkausl
Nov 13 '18 at 18:06





You allocate 3 cppUr but then use 4.

– tkausl
Nov 13 '18 at 18:06




2




2





And you should not ever delete uName. It is statically allocated, not dynamically. There is also no reason to dynamically allocate cpp and if you are learning C++, you should use std::string instead of all the char, char*, strncpy and manual dynamic memory management.

– user10605163
Nov 13 '18 at 18:11






And you should not ever delete uName. It is statically allocated, not dynamically. There is also no reason to dynamically allocate cpp and if you are learning C++, you should use std::string instead of all the char, char*, strncpy and manual dynamic memory management.

– user10605163
Nov 13 '18 at 18:11





2




2





This would be much simpler with std::string instead of C-style strings.

– Pete Becker
Nov 13 '18 at 18:19





This would be much simpler with std::string instead of C-style strings.

– Pete Becker
Nov 13 '18 at 18:19




1




1





Note that strncpy is not a "safe" replacement for strcpy, for any reasonable definition of "safe". Read its documentation carefully.

– Pete Becker
Nov 13 '18 at 18:20





Note that strncpy is not a "safe" replacement for strcpy, for any reasonable definition of "safe". Read its documentation carefully.

– Pete Becker
Nov 13 '18 at 18:20












1 Answer
1






active

oldest

votes


















0














The error is very simple.



You create array from ccpUr with 3 elements, but after use 4 of them.



Of course the c++ is null based index language, but that means the last is not useable. That is why in your for cycle condition must be use the same number in like in array allocation which is the 3.



Think about it, when [3] is enough for 4 element then the [2] is enough for 3 element then [1] is enough for 2 element, and [0] is enough for 1 element? Do you feel it? The zero size array is not enough for nothing.



regards






share|improve this answer























  • But array is starting from 0? When I create array [3], it should be include [0], [1], [2],[3] and total 4 ?

    – wong waiman
    Nov 13 '18 at 20:08












  • no, it is not true. If you have right, the array[0] is still contains one element. when you define array[3] the index3 must be not used. in the for condition you have to use i < 3. It means the 3 will be not used.

    – György Gulyás
    Nov 14 '18 at 11:07












  • Hello wong. Is it clear now? If not, just ask it. tthx

    – György Gulyás
    Nov 16 '18 at 20:14











  • Thank you, I understand the logic

    – wong waiman
    Nov 17 '18 at 21:37











  • Welcome :) And please upvote my answer, thx :)

    – György Gulyás
    Nov 18 '18 at 13:12










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1 Answer
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1 Answer
1






active

oldest

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active

oldest

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active

oldest

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0














The error is very simple.



You create array from ccpUr with 3 elements, but after use 4 of them.



Of course the c++ is null based index language, but that means the last is not useable. That is why in your for cycle condition must be use the same number in like in array allocation which is the 3.



Think about it, when [3] is enough for 4 element then the [2] is enough for 3 element then [1] is enough for 2 element, and [0] is enough for 1 element? Do you feel it? The zero size array is not enough for nothing.



regards






share|improve this answer























  • But array is starting from 0? When I create array [3], it should be include [0], [1], [2],[3] and total 4 ?

    – wong waiman
    Nov 13 '18 at 20:08












  • no, it is not true. If you have right, the array[0] is still contains one element. when you define array[3] the index3 must be not used. in the for condition you have to use i < 3. It means the 3 will be not used.

    – György Gulyás
    Nov 14 '18 at 11:07












  • Hello wong. Is it clear now? If not, just ask it. tthx

    – György Gulyás
    Nov 16 '18 at 20:14











  • Thank you, I understand the logic

    – wong waiman
    Nov 17 '18 at 21:37











  • Welcome :) And please upvote my answer, thx :)

    – György Gulyás
    Nov 18 '18 at 13:12















0














The error is very simple.



You create array from ccpUr with 3 elements, but after use 4 of them.



Of course the c++ is null based index language, but that means the last is not useable. That is why in your for cycle condition must be use the same number in like in array allocation which is the 3.



Think about it, when [3] is enough for 4 element then the [2] is enough for 3 element then [1] is enough for 2 element, and [0] is enough for 1 element? Do you feel it? The zero size array is not enough for nothing.



regards






share|improve this answer























  • But array is starting from 0? When I create array [3], it should be include [0], [1], [2],[3] and total 4 ?

    – wong waiman
    Nov 13 '18 at 20:08












  • no, it is not true. If you have right, the array[0] is still contains one element. when you define array[3] the index3 must be not used. in the for condition you have to use i < 3. It means the 3 will be not used.

    – György Gulyás
    Nov 14 '18 at 11:07












  • Hello wong. Is it clear now? If not, just ask it. tthx

    – György Gulyás
    Nov 16 '18 at 20:14











  • Thank you, I understand the logic

    – wong waiman
    Nov 17 '18 at 21:37











  • Welcome :) And please upvote my answer, thx :)

    – György Gulyás
    Nov 18 '18 at 13:12













0












0








0







The error is very simple.



You create array from ccpUr with 3 elements, but after use 4 of them.



Of course the c++ is null based index language, but that means the last is not useable. That is why in your for cycle condition must be use the same number in like in array allocation which is the 3.



Think about it, when [3] is enough for 4 element then the [2] is enough for 3 element then [1] is enough for 2 element, and [0] is enough for 1 element? Do you feel it? The zero size array is not enough for nothing.



regards






share|improve this answer













The error is very simple.



You create array from ccpUr with 3 elements, but after use 4 of them.



Of course the c++ is null based index language, but that means the last is not useable. That is why in your for cycle condition must be use the same number in like in array allocation which is the 3.



Think about it, when [3] is enough for 4 element then the [2] is enough for 3 element then [1] is enough for 2 element, and [0] is enough for 1 element? Do you feel it? The zero size array is not enough for nothing.



regards







share|improve this answer












share|improve this answer



share|improve this answer










answered Nov 13 '18 at 18:20









György GulyásGyörgy Gulyás

554424




554424












  • But array is starting from 0? When I create array [3], it should be include [0], [1], [2],[3] and total 4 ?

    – wong waiman
    Nov 13 '18 at 20:08












  • no, it is not true. If you have right, the array[0] is still contains one element. when you define array[3] the index3 must be not used. in the for condition you have to use i < 3. It means the 3 will be not used.

    – György Gulyás
    Nov 14 '18 at 11:07












  • Hello wong. Is it clear now? If not, just ask it. tthx

    – György Gulyás
    Nov 16 '18 at 20:14











  • Thank you, I understand the logic

    – wong waiman
    Nov 17 '18 at 21:37











  • Welcome :) And please upvote my answer, thx :)

    – György Gulyás
    Nov 18 '18 at 13:12

















  • But array is starting from 0? When I create array [3], it should be include [0], [1], [2],[3] and total 4 ?

    – wong waiman
    Nov 13 '18 at 20:08












  • no, it is not true. If you have right, the array[0] is still contains one element. when you define array[3] the index3 must be not used. in the for condition you have to use i < 3. It means the 3 will be not used.

    – György Gulyás
    Nov 14 '18 at 11:07












  • Hello wong. Is it clear now? If not, just ask it. tthx

    – György Gulyás
    Nov 16 '18 at 20:14











  • Thank you, I understand the logic

    – wong waiman
    Nov 17 '18 at 21:37











  • Welcome :) And please upvote my answer, thx :)

    – György Gulyás
    Nov 18 '18 at 13:12
















But array is starting from 0? When I create array [3], it should be include [0], [1], [2],[3] and total 4 ?

– wong waiman
Nov 13 '18 at 20:08






But array is starting from 0? When I create array [3], it should be include [0], [1], [2],[3] and total 4 ?

– wong waiman
Nov 13 '18 at 20:08














no, it is not true. If you have right, the array[0] is still contains one element. when you define array[3] the index3 must be not used. in the for condition you have to use i < 3. It means the 3 will be not used.

– György Gulyás
Nov 14 '18 at 11:07






no, it is not true. If you have right, the array[0] is still contains one element. when you define array[3] the index3 must be not used. in the for condition you have to use i < 3. It means the 3 will be not used.

– György Gulyás
Nov 14 '18 at 11:07














Hello wong. Is it clear now? If not, just ask it. tthx

– György Gulyás
Nov 16 '18 at 20:14





Hello wong. Is it clear now? If not, just ask it. tthx

– György Gulyás
Nov 16 '18 at 20:14













Thank you, I understand the logic

– wong waiman
Nov 17 '18 at 21:37





Thank you, I understand the logic

– wong waiman
Nov 17 '18 at 21:37













Welcome :) And please upvote my answer, thx :)

– György Gulyás
Nov 18 '18 at 13:12





Welcome :) And please upvote my answer, thx :)

– György Gulyás
Nov 18 '18 at 13:12



















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