#include<stdio.h>
#include<string.h>
#include<malloc.h>
int main()
{
char *name;
int a;
name=(char *)malloc(sizeof(name));
printf("no. of names:");
scanf("%d",&a);
int i;
for(i=0;i<a;i++)
{
printf("enter the names:");
scanf("%s",name);
}
for(i=0;i<a;i++)
{
printf("entered names are:%s\n",name);
}
return 0;
free(name);
}
how to print n numbers of entered string in c am already asked this question but i dont got any proper answer any body known the answer please edit my code please if you run my code its displays last string only i dont know why please help..
You need an array of names. To achieve what you are trying to do you can use either a static array with the maximum size or allocate the memory dinamically as in the following program.
Note that you should also test the return value of malloc... just in case.
#include<stdio.h>
#include<string.h>
#include<malloc.h>
int main()
{
char **name;
int a;
printf("no. of names:");
scanf("%d",&a);
int i;
if( a<=0 )
return 0;
name = (char**)malloc( sizeof(char*)*a);
for(i=0;i<a;i++)
{
printf("enter the name:");
name[i]=(char*)malloc( sizeof(char)*128);
scanf("%s",name[i]);
}
for(i=0;i<a;i++)
{
printf("entered names are:%s\n",name[i]);
free(name[i]);
}
free(name);
return(0);
}
Note I had to cast malloc because the compiler that the OP is using raise the error " cannot convert from 'void ' to 'char ** ' " (which means that it's old enough..)
In
name=(char *)malloc(sizeof(name));
name is a char*, so sizeof(name) is the size of an address. Hence you are not allocating enough memory.
Just allocate more memory:
name=(char *)malloc(sizeof(char)*20); //allocating 20 bytes for the block that name will point tor
In addition to wrong space allocation (answered by brokenfoot), you will not get the results you want because you are reading all the names over and over in the same variable name, and later printing the name input last a times:
for(i=0;i<a;i++)
{
printf("enter the names:");
scanf("%s",name);
}
for(i=0;i<a;i++)
{
printf("entered names are:%s\n",name);
}
The right approach would be to use an array to store all the names, and later print them one by one. For example:
for(i=0;i<a;i++)
{
printf("Enter the names:")
scanf("%s",name[a]);
}
print("The entered names are: ");
for(i=0;i<a;i++)
{
printf("%s", name[a]);
}
Related
#include<stdio.h>
#include<conio.h>
main()
{
char name[25];
printf("Enter Your Full Name:");
int i = 0;
name[i] = getche();
while(name[i] != '\r')
{
i++;
name[i] = getche();
}
printf("\n%s\n", name);
system("pause");
}
On execution when I enter name Razwan Muzaffar I am getting the wrong output. While with some other names the output is Ok. But when I try some other names, makes trouble. Carriage return or buffer memory flush, I think something like is a point of consideration.
I am absolute beginner. So kindly explain the issue.
So i have a problem. I have to separate the first name, last name and hostname of email.
For example:
zephyr.extreme#gmail.com>> Input
Output=
First name= Zephyr
Last name= extreme
Host Name= gmail.com
I am not getting the desired result. I am getting some weird shapes as output.
Code:
#include <stdio.h>
int main()
{
char email[40], first[20],last[20],host[30];
printf("Enter the email= ");
gets(email);
int i;
while(email[i]!='\0')
{
while(email[i]!='.')
{
first[i]=email[i];
i++;
}
while(email[i]!='#')
{
last[i]=email[i];
i++;
}
while(email[i]!='\0')
{
host[i]=email[i];
i++;
}
}
puts(first);
puts(last);
puts(host);
}
Assuming the format will always be first.last#host..., use this code:
#include <stdio.h>
#include <string.h>
int main()
{
char email[40], first[20],last[20],host[30],name[40];
int firstDot,atSymbol;
int i;
int length;
char *token;
printf("Enter the email= ");
gets(email);
length = strlen(email);
for(i=0;i<length;i++){
if(email[i]=='.')
{
firstDot = i;
}
else if(email[i]=='#')
{
atSymbol = i;
}
}
strncpy(name,email,atSymbol);
name[atSymbol]= '\0';
token = strtok(name, ".");
/* walk through other tokens */
while( token != NULL )
{
printf( "%s\n", token );
token = strtok(NULL, ".");
}
strncpy(host,email+atSymbol,length-atSymbol);
host[length-atSymbol] = '\0';
puts(host);
}
So i updated the code, now the only problem is the last output.
After host name= gmail.com prints, but then some extra shapes are also printing. These are smile face and some weird symbols.
Code:
#include <stdio.h>
int main()
{
char email[40], first[20],last[20],host[30];
printf("Enter the email= ");
gets(email);
int i=0,j;
while(email[i]!='.')
{
first[i]=email[i];
i++;
}
i=0;
while(email[i]!='#')
{
last[i]=email[i];
i++;
}
j=i;
i=0;
while(email[j]!='\0')
{
host[i]=email[j];
j++;
i++;
}
printf("First Name= ");
puts(first);
printf("Last name= ");
puts(last);
printf("Host name= ");
puts(host);
}
C strings (char pointers) should be null-terminated. This means your string needs a '\0' character at its end so that string manipulation functions such as puts or strlen know where they end, in constrast to other languages where the string's length is stored together with it. The "weird shapes" you are seeing are just random data stored after the end of the string being interpreted as characters. When you call puts it just keeps outputting bytes-as-characters until it randomly finds a byte with value '\0'
You can solve this by adding a '\0' character to the end of the string after each of the blocks where you write a string.
while(email[i]!='.')
{
first[i]=email[i];
i++;
}
email[i] = '\0'; //same thing as email[i] = 0; but using a char makes what
//you're doing clearer
I have a question concerning working with classes in c++. I must say I'm a beginner. For example, i have this class:
class student {
private:
char* name;
public:
int nrcrt;
student() {
name = new char[7];
name = "Anonim";
nrcrt = 0;
}
student(char* n, int n) {
this->name = new char[7];
strcpy(name, n);
nrcrt = nr;
}
~student() {
delete [] name;
}
char* get_name() {
return this->name;
}
}
void main() {
student group[3];
group[0] = student("Ana", 1);
group[1] = student("Alex", 2);
group[2] = student("Liam", 5);
for (i=0; i<3; i++) {
if (group.nrcrt[i] != 0)
cout << group[i].get_name() << Endl;
}
}
My question is why is it displaying different characters?
first of all your code is not working.
3.cpp:40:18: error: request for member ‘nrcrt’ in ‘group’, which is of non-class type ‘student [3]’
if(group.nrcrt[i]!=0)
i is also not declared.please make proper changes.
group.nrcrt[i]
should be changed to:
group[i].nrcrt
When the array is created, your default constructor is used.
When you assign to the elements, your destructor is called, deleting name.
The default constructor is assigning a literal to name, and deleting that memory has undefined behaviour.
In your default constructor, replace
name = "Anonim";
with
strcpy(name, "Anonim");
Your compiler should have warned you about the assignment.
If it didn't, increase the warning level of your compiler.
If it did, start listening to your compiler's warnings.
do not worry. C++ could look a bit scary as first but it is ok when you get into it. First, let's say that all classes it is good to start with upper case letters. Secondly, you have two constructors (default without parameters and one or more with, in our case one). Default consructor you need to declare an array of objects:
Student group[3];
The next important thing is that you then do not need the rest of the constructors in that case.
group[0]=student("Ana",1);
group[1]=student("Alex",2);
group[2]=student("Liam",5);
Remember to include ; at the end of class declaration. To put all the statements and expression throughout your interation within the same loop. Here is what I found as an errors anf fix them. Could probably have more.
class Student
{
private:
char* name;
public:
int nrcrt;
Student()
{
name=new char[7];
strcpy(name, "Anonim");
nrcrt=0;
}
Student( char* n, int n)
{
this->name=new char[7];
strcpy(name, n);
nrcrt=nr;
}
~Student()
{
delete [] name;
}
char* get_name()
{
return this->name;
}
};
int main()
{
Student group[3];
for(int i=0;i<3;i++)
{
if(group.nrcrt[i]!=0)
cout<<group[i].get_name()<<endl;
}
return 0;
}
as we know it in C, a string defining is,
char string[] = "Hello World";
That is OK,
But I want to use a function and at initial same up,
I tried those, For example;
char * to_string()
{
return "Hello World";
}
Or;
char * to_String(void) // Function
{
char buff[16];
sprintf(buff, "%s", "Hello World");
return buff;
}
main() // main function
{
char Initial_String[] = to_String();
}
How to make this or any idea same another way.
I find what I dont send address of char Initial_String[] to fill into. No. is there Another method.
Thanks.
When you compile this, atleast in GCC, it will give you the following warning:
b.c:9: warning: function returns address of local variable
Why? Because buff[] is a local variable of function to_string(). Its scope is only inside the function to_string(). main() does not have any access to this variable. Try making buff[] a global variable instead.
Second problem: char Initial_String[] = to_String(); cannot be assigned value in this way. to_string() returns a char pointer, hence assign the value thus:
char *Initial_String = to_String();
The code below will work:
char buff[16];
char* to_String(void) // Function
{
//char buff[16]; /*this is a local variable*/
sprintf(buff, "%s", "Hello World");
return buff;
}
int main(void) // main function
{
char *Initial_String = to_String();
printf("%s", Initial_String);
return 0;
}
Yes You are right about local buffer mismake,
But This is not my wanting,
if I edit some differently,
char buff[16];
char* to_String(void) // Function
{
//char buff[16]; /*this is a local variable*/
sprintf(buff, "%s", "Hello World");
return buff;
}
int main(void) // main function
{
char *Initial_String_1 = to_String();
char *Initial_String_2 = to_String();
char *Initial_String_3 = to_String();
printf("%s", Initial_String_1 );
printf("%s", Initial_String_2 );
printf("%s", Initial_String_3 );
in this case, all strings will be same, because They have same buffer address,
I want to open the topic little more.
struct
{
long aaa;
short bbb;
int ccc;
char ddd;
.
.
. // the list goes on
}elements;
typedef struct
{
int lengt;
int *adress;
char name[10];
}_list;
char* to_String(long variable) // Function
{
sprintf(buff, "%ld", variable);
return buff;
}
int main (void)
{
_list My_List[] = {
{ sizeof(elements.aaa), &elements.aaa , to_string( elements.aaa) },
{ sizeof(elements.bbb), &elements.bbb , to_string( elements.bbb) },
{ sizeof(elements.ccc), &elements.ccc , to_string( elements.ddd) },
.
.
. //// the list goes on
};
I do not know, Do I make myself clear.
Here, string must be filled into name array, without assigning it the address.
I may have syntax mistake. the code is not tested with compiler. the idea is for illustrative purposes only.
I am trying to find a method for The purpose.
Thanks.
I have invalid read of size in the following functions using valgrind. I'm not exactly sure why but if any of you can help me that would be greatly appreciated! From what I can tell it runs okay but there are still some errors that I'm not catching that may even deal with memory allocation and deallocation. Please help!
//alternate constructor that allows for setting of the inital value of the string
MyString::MyString(const char *message)
{
int counter(0);
while(message[counter] != '\0')
{
counter++;
}
Size = counter;
**String = new char [Size];**
for(int i=0; i < Size; i++)
String[i] = message[i];
}
istream& operator>>(istream& input, MyString& rhs)
{
char* t;
int size(256);
t = new char[size];
input.getline(t,size);
**rhs = MyString(t);**
delete [] t;
return input;
}
/*Assignment operator (=) which will copy the source string into the destination string. Note that size of the destination needs to be adjusted to be the same as the source.
*/
MyString& MyString::operator=(const MyString& rhs)
{
if(this != &rhs)
{
delete [] String;
**String = new char[rhs.Size+1];**
Size = rhs.Size;
for(int i = 0; i < Size; i++)
{
** String[i] = rhs.String[i];**
}
}
return *this;
}
Any suggestions?? (All of the problem lines have **)
One thing I see is that your copy constructor doesn't allocate space for \0 and doesn't copy it. Neither does the assignment operator.. Or, if you don't store terminating zero, then why are you looking for it?
and the two implementations differ, why the inconsistency (Size vs counter)?
"From what I can tell it runs okay" - it's called undefined behaviour, or in this case: luck - or, if you like me, and like to catch bugs: a misfortune.