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Engineering Computer Science C++ How to Program (Early Objects Version)

Program plan: Rewrite all memory handling functions using pointer arithmetic. Here is a list of functions. To avoid the conflict with existing cstring library functions change the names of functions in the program. 1- void* memcpy(void* s1, const void* s2, size_t n) 2- void* memmove(void* s1, const void* s2, size_t n) 3- int memcmp(const void* s1, const void* s2, size_t n) 4- void* memchr(const void* s, int c, size_t n) 5- void* memset(void* s, int c, size_t n) Program Description: The following program rewrite its own version of memory handling functions shown in figure 22.41. Program: #include<cctype> #include<iostream> #include<cstring> usingnamespace std; void*Memcpy(void* s1,constvoid* s2,size_t n){ char*csrc=(char*)s2; char*cdest=(char*)s1; // Copy contents of src[] to dest[] for(inti=0;i< n;i++) cdest[i]=csrc[i]; cdest[n]='\0'; } void*Memmove(void* s1,constvoid* s2,size_t n){ char*csrc=(char*)s2; char*cdest=(char*)s1; // Create a temporary array to hold data of src char*temp =newchar[n]; // Copy data from csrc[] to temp[] for(inti=0;i<n;i++) temp[i]=csrc[i]; // Copy data from temp[] to cdest[] for(inti=0;i<n;i++) cdest[i]= temp[i]; cdest[n]='\0'; delete[] temp; } intMemcmp(constvoid* s1,constvoid* s2,size_t n){ size_ti; /& * s1 and s2 are the same memory? */ if(s1 == s2) { return0; } // This for loop does the comparing and pointer moving... for(i=0;(i< n)&&(*(char*)s1 ==*(char*)s2); i++, s1 =1+(char*)s1, s2 =1+(char*)s2); //if i == length, then we have passed the test return(i== n)?0:(*(char*)s1 -*(char*)s2); } void*Memchr(constvoid* s,int c,size_t count){ inti; char*str =(char*)s; for(i=0;i< count ;i++) { if(*str == c){ return str; } else str++; } } void*Memset(void* s,int c,size_t n){ inti; char*str =(char*)s; for(i=0;i< n ;i++) { str[i]= c; } } intmain() { int choice =0,num=0; char*cptr; char s1[50]; char s2[50]; char c; int c1; cout<<"================MAIN MENU====================="<<endl; cout<<"1- Copy n characters from the s2 object into the object s1"<<endl; cout<<"2- Copy n characters from the s2 object into the object s1 using temp memory"<<endl; cout<<"3- Compares the first n characters of the objects pointed to by s1 and s2 "<<endl; cout<<"4- Locates the first occurrence of c in the first n chars of the s object"<<endl; cout<<"5- Copies c chars into the first n characters of the s object"<<endl; cout<<"6- Quit"<<endl; cout<<"Enter your choice"<<endl; cin>>choice; while(choice <6&& choice >0){ switch(choice){ case1: cout<<"Enter Source String s2 >> "; cin.ignore(); cin.getline(s2,50); cout<<"Enter no. of char to be copied to s1 >> "; cin>>num; Memcpy(s1,s2,num); cout<<"s1 After Memcpy is >> "<<s1<<endl; break; case2: cout<<"Enter Source String s2 >> "; cin.ignore(); cin.getline(s2,50); cout<<"Enter no. of char to be copied to s1 >> "; cin>>num; Memmove(s1,s2,num); cout<<"s1 After Memmove is >> "<<s1<<endl; break; case3: cout<<"Enter String s1 >> "; cin.ignore(); cin.getline(s1,50); cout<<"Enter String s2 >> "; cin.getline(s2,50); if(Memcmp(s1,s2,5)==0){ cout<<"s1 and s2 match"<<endl; }else{ cout<<"s1 and s2 do not match"<<endl; } break; case4: cout<<"Enter String >> "; cin.ignore(); cin.getline(s1,50); cout<<"Enter char >> "; cin>> c; cin.ignore(); cout<<"Enter length >> "; cin>>num; cout<<"Char \'"<< c <<"\' appeared in string \'"<<s1 <<"\' and returned string is "<<(char*)Memchr(s1,c,num)<<endl; break; case5: cout<<"Enter String >> "; cin.ignore(); cin.getline(s1,50); cout<<"Enter char >> "; cin>> c; cin.ignore(); cout<<"Enter length >> "; cin>>num; Memset(s1,c,num); cout<<"string s1 after memset is >> "<<s1<<endl; break; default: cout<<"Please choose the right option"<<endl; break; } cout<<"1- Copy n characters from the s2 object into the object s1"<<endl; cout<<"2- Copy n characters from the s2 object into the object s1 using temp memory"<<endl; cout<<"3- Compares the first n characters of the objects pointed to by s1 and s2 "<<endl; cout<<"4- Locates the first occurrence of c in the first n chars of the s object"<<endl; cout<<"5- Copies c chars into the first n characters of the s object"<<endl; cout<<"6- Quit"<<endl; cout<<"Enter your choice"<<endl; cin>>choice; } return0; } Sample Output ================MAIN MENU===================== 1- Copy n characters from the s2 object into the object s1 2- Copy n characters from the s2 object into the object s1 using temp memory 3- Compares the first n characters of the objects pointed to by s1 and s2 4- Locates the first occurrence of c in the first n chars of the s object 5- Copies c chars into the first n characters of the s object 6- Quit Enter your choice 1 Enter Source String s2 >> this is test string Enter no. of char to be copied to s1 >> 5 s1 After Memcpy is >> this 1- Copy n characters from the s2 object into the object s1 2- Copy n characters from the s2 object into the object s1 using temp memory 3- Compares the first n characters of the objects pointed to by s1 and s2 4- Locates the first occurrence of c in the first n chars of the s object 5- Copies c chars into the first n characters of the s object 6- Quit Enter your choice 2 Enter Source String s2 >> Marry had a little lamb Enter no. of char to be copied to s1 >> 12 s1 After Memmove is >> Marry had a 1- Copy n characters from the s2 object into the object s1 2- Copy n characters from the s2 object into the object s1 using temp memory 3- Compares the first n characters of the objects pointed to by s1 and s2 4- Locates the first occurrence of c in the first n chars of the s object 5- Copies c chars into the first n characters of the s object 6- Quit Enter your choice 3 Enter String s1 >> Jack & Jill Enter String s2 >> went up the hill s1 and s2 do not match 1- Copy n characters from the s2 object into the object s1 2- Copy n characters from the s2 object into the object s1 using temp memory 3- Compares the first n characters of the objects pointed to by s1 and s2 4- Locates the first occurrence of c in the first n chars of the s object 5- Copies c chars into the first n characters of the s object 6- Quit Enter your choice 3 Enter String s1 >> Jack & jill Enter String s2 >> Jack & jill s1 and s2 match 1- Copy n characters from the s2 object into the object s1 2- Copy n characters from the s2 object into the object s1 using temp memory 3- Compares the first n characters of the objects pointed to by s1 and s2 4- Locates the first occurrence of c in the first n chars of the s object 5- Copies c chars into the first n characters of the s object 6- Quit Enter your choice 4 Enter String >> Rain Rain go away Enter char >> o Enter length >> 12 Char 'o' appeared in string 'Rain Rain go away' and returned string is o away 1- Copy n characters from the s2 object into the object s1 2- Copy n characters from the s2 object into the object s1 using temp memory 3- Compares the first n characters of the objects pointed to by s1 and s2 4- Locates the first occurrence of c in the first n chars of the s object 5- Copies c chars into the first n characters of the s object 6- Quit Enter your choice 5 Enter String >> Checking final string Enter char >> a Enter length >> 5 string s1 after memset is >>aaaaaing final string 1- Copy n characters from the s2 object into the object s1 2- Copy n characters from the s2 object into the object s1 using temp memory 3- Compares the first n characters of the objects pointed to by s1 and s2 4- Locates the first occurrence of c in the first n chars of the s object 5- Copies c chars into the first n characters of the s object 6- Quit Enter your choice 6

Program plan: Rewrite all memory handling functions using pointer arithmetic. Here is a list of functions. To avoid the conflict with existing cstring library functions change the names of functions in the program. 1- void* memcpy(void* s1, const void* s2, size_t n) 2- void* memmove(void* s1, const void* s2, size_t n) 3- int memcmp(const void* s1, const void* s2, size_t n) 4- void* memchr(const void* s, int c, size_t n) 5- void* memset(void* s, int c, size_t n) Program Description: The following program rewrite its own version of memory handling functions shown in figure 22.41. Program: #include<cctype> #include<iostream> #include<cstring> usingnamespace std; voidMemcpy(void s1,constvoid* s2,size_t n){ charcsrc=(char)s2; charcdest=(char)s1; // Copy contents of src[] to dest[] for(inti=0;i< n;i++) cdest[i]=csrc[i]; cdest[n]='\0'; } voidMemmove(void s1,constvoid* s2,size_t n){ charcsrc=(char)s2; charcdest=(char)s1; // Create a temporary array to hold data of src chartemp =newchar[n]; // Copy data from csrc[] to temp[] for(inti=0;i<n;i++) temp[i]=csrc[i]; // Copy data from temp[] to cdest[] for(inti=0;i<n;i++) cdest[i]= temp[i]; cdest[n]='\0'; delete[] temp; } intMemcmp(constvoid s1,constvoid* s2,size_t n){ size_ti; /& * s1 and s2 are the same memory? / if(s1 == s2) { return0; } // This for loop does the comparing and pointer moving... for(i=0;(i< n)&&((char)s1 ==(char)s2); i++, s1 =1+(char)s1, s2 =1+(char)s2); //if i == length, then we have passed the test return(i== n)?0:((char)s1 -(char)s2); } voidMemchr(constvoid* s,int c,size_t count){ inti; charstr =(char)s; for(i=0;i< count ;i++) { if(str == c){ return str; } else str++; } } voidMemset(void* s,int c,size_t n){ inti; charstr =(char)s; for(i=0;i< n ;i++) { str[i]= c; } } intmain() { int choice =0,num=0; charcptr; char s1[50]; char s2[50]; char c; int c1; cout<<"================MAIN MENU====================="<<endl; cout<<"1- Copy n characters from the s2 object into the object s1"<<endl; cout<<"2- Copy n characters from the s2 object into the object s1 using temp memory"<<endl; cout<<"3- Compares the first n characters of the objects pointed to by s1 and s2 "<<endl; cout<<"4- Locates the first occurrence of c in the first n chars of the s object"<<endl; cout<<"5- Copies c chars into the first n characters of the s object"<<endl; cout<<"6- Quit"<<endl; cout<<"Enter your choice"<<endl; cin>>choice; while(choice <6&& choice >0){ switch(choice){ case1: cout<<"Enter Source String s2 >> "; cin.ignore(); cin.getline(s2,50); cout<<"Enter no. of char to be copied to s1 >> "; cin>>num; Memcpy(s1,s2,num); cout<<"s1 After Memcpy is >> "<<s1<<endl; break; case2: cout<<"Enter Source String s2 >> "; cin.ignore(); cin.getline(s2,50); cout<<"Enter no. of char to be copied to s1 >> "; cin>>num; Memmove(s1,s2,num); cout<<"s1 After Memmove is >> "<<s1<<endl; break; case3: cout<<"Enter String s1 >> "; cin.ignore(); cin.getline(s1,50); cout<<"Enter String s2 >> "; cin.getline(s2,50); if(Memcmp(s1,s2,5)==0){ cout<<"s1 and s2 match"<<endl; }else{ cout<<"s1 and s2 do not match"<<endl; } break; case4: cout<<"Enter String >> "; cin.ignore(); cin.getline(s1,50); cout<<"Enter char >> "; cin>> c; cin.ignore(); cout<<"Enter length >> "; cin>>num; cout<<"Char \'"<< c <<"\' appeared in string \'"<<s1 <<"\' and returned string is "<<(char)Memchr(s1,c,num)<<endl; break; case5: cout<<"Enter String >> "; cin.ignore(); cin.getline(s1,50); cout<<"Enter char >> "; cin>> c; cin.ignore(); cout<<"Enter length >> "; cin>>num; Memset(s1,c,num); cout<<"string s1 after memset is >> "<<s1<<endl; break; default: cout<<"Please choose the right option"<<endl; break; } cout<<"1- Copy n characters from the s2 object into the object s1"<<endl; cout<<"2- Copy n characters from the s2 object into the object s1 using temp memory"<<endl; cout<<"3- Compares the first n characters of the objects pointed to by s1 and s2 "<<endl; cout<<"4- Locates the first occurrence of c in the first n chars of the s object"<<endl; cout<<"5- Copies c chars into the first n characters of the s object"<<endl; cout<<"6- Quit"<<endl; cout<<"Enter your choice"<<endl; cin>>choice; } return0; } Sample Output ================MAIN MENU===================== 1- Copy n characters from the s2 object into the object s1 2- Copy n characters from the s2 object into the object s1 using temp memory 3- Compares the first n characters of the objects pointed to by s1 and s2 4- Locates the first occurrence of c in the first n chars of the s object 5- Copies c chars into the first n characters of the s object 6- Quit Enter your choice 1 Enter Source String s2 >> this is test string Enter no. of char to be copied to s1 >> 5 s1 After Memcpy is >> this 1- Copy n characters from the s2 object into the object s1 2- Copy n characters from the s2 object into the object s1 using temp memory 3- Compares the first n characters of the objects pointed to by s1 and s2 4- Locates the first occurrence of c in the first n chars of the s object 5- Copies c chars into the first n characters of the s object 6- Quit Enter your choice 2 Enter Source String s2 >> Marry had a little lamb Enter no. of char to be copied to s1 >> 12 s1 After Memmove is >> Marry had a 1- Copy n characters from the s2 object into the object s1 2- Copy n characters from the s2 object into the object s1 using temp memory 3- Compares the first n characters of the objects pointed to by s1 and s2 4- Locates the first occurrence of c in the first n chars of the s object 5- Copies c chars into the first n characters of the s object 6- Quit Enter your choice 3 Enter String s1 >> Jack & Jill Enter String s2 >> went up the hill s1 and s2 do not match 1- Copy n characters from the s2 object into the object s1 2- Copy n characters from the s2 object into the object s1 using temp memory 3- Compares the first n characters of the objects pointed to by s1 and s2 4- Locates the first occurrence of c in the first n chars of the s object 5- Copies c chars into the first n characters of the s object 6- Quit Enter your choice 3 Enter String s1 >> Jack & jill Enter String s2 >> Jack & jill s1 and s2 match 1- Copy n characters from the s2 object into the object s1 2- Copy n characters from the s2 object into the object s1 using temp memory 3- Compares the first n characters of the objects pointed to by s1 and s2 4- Locates the first occurrence of c in the first n chars of the s object 5- Copies c chars into the first n characters of the s object 6- Quit Enter your choice 4 Enter String >> Rain Rain go away Enter char >> o Enter length >> 12 Char 'o' appeared in string 'Rain Rain go away' and returned string is o away 1- Copy n characters from the s2 object into the object s1 2- Copy n characters from the s2 object into the object s1 using temp memory 3- Compares the first n characters of the objects pointed to by s1 and s2 4- Locates the first occurrence of c in the first n chars of the s object 5- Copies c chars into the first n characters of the s object 6- Quit Enter your choice 5 Enter String >> Checking final string Enter char >> a Enter length >> 5 string s1 after memset is >>aaaaaing final string 1- Copy n characters from the s2 object into the object s1 2- Copy n characters from the s2 object into the object s1 using temp memory 3- Compares the first n characters of the objects pointed to by s1 and s2 4- Locates the first occurrence of c in the first n chars of the s object 5- Copies c chars into the first n characters of the s object 6- Quit Enter your choice 6

Solution Summary: The author explains how the following program rewrites its own version of memory handling functions using pointer arithmetic.

C++ How to Program (Early Objects Version)

C++ How to Program (Early Objects Version)

10th Edition

ISBN: 9780134448824

Author: Paul Deitel; Harvey M. Deitel

Publisher: Pearson Education (US)

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Chapter 22, Problem 22.27E

Chapter 22, Problem 22.29E

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Chapter 22 Solutions

C++ How to Program (Early Objects Version)

Ch. 22 - Prob. 22.4E Ch. 22 - Prob. 22.5E Ch. 22 - (Shifting and Printing an Integer) Write a program...Ch. 22 - (Multiplication Via Bit Shifting) Left-shifting as...Ch. 22 - (Packing Characters into Unsigned Integers) The...Ch. 22 - (Unpacking Characters from Unsigned Integers)...Ch. 22 - Prob. 22.10E Ch. 22 - Prob. 22.11E Ch. 22 - (Determine the Value) The following program uses...Ch. 22 - Prob. 22.13E

Ch. 22 - Prob. 22.14E Ch. 22 - (Converting Strings to Integers) Write program...Ch. 22 - Prob. 22.16E Ch. 22 - (searching for Substrings) Write a program that...Ch. 22 - (Searching for Substrings) Write a program based...Ch. 22 - Prob. 22.19E Ch. 22 - Prob. 22.20E Ch. 22 - (ASCII Character Set) The chart in Appendix B...Ch. 22 - Prob. 22.22E Ch. 22 - Prob. 22.23E Ch. 22 - (Displaying Characters for Given ASCII Codes)...Ch. 22 - Prob. 22.25E Ch. 22 - Prob. 22.26E Ch. 22 - Prob. 22.27E Ch. 22 - Prob. 22.28E Ch. 22 - Prob. 22.29E Ch. 22 - Prob. 22.30E Ch. 22 - Prob. 22.31E Ch. 22 - (Limericks) A limerick is a humorous five-line...Ch. 22 - Prob. 22.33E Ch. 22 - Prob. 22.34E Ch. 22 - Prob. 22.35E Ch. 22 - Prob. 22.36E Ch. 22 - Prob. 22.37E Ch. 22 - Prob. 22.38E Ch. 22 - Prob. 22.39E Ch. 22 - Prob. 22.40E Ch. 22 - Prob. 22.41E Ch. 22 - (Word Processing) One important function in...Ch. 22 - (Printing Dates in Various Formats) Dates are...Ch. 22 - (Check Protection) Computers are frequently in...Ch. 22 - (Writing the Word Equivalent of a Check Amount)...Ch. 22 - (Morse Code) Perhaps the most famous of all coding...Ch. 22 - Prob. 22.47E Ch. 22 - (Crossword Puzzle Generator) Most people have...Ch. 22 - (Spelling Checker) Many popular word-processing...

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