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I've declared a struct and a pointer array by the declared struct.
struct Book* Collection[100];
Before the code ends I want to free up my memory using free function. free function is called up after printf() at printCollection()
void printCollection(struct Book* col, int num) {
int i;
for (i = 0; i < num; i++) {
printf("Name: %s Author: %s Page: %d Price: %d\n", col[i].name, col[i].author, col[i].page, col[i].price);
free(col[i]);
}
}
but I can't even build the program because of a error. Could I get some help?
You need to change printCollection to look like this:
void printCollection(struct Book* col[], int num) {
int i;
for (i = 0; i < num; i++) {
printf("Name: %s Author: %s Page: %d Price: %d\n",
col[i]->name, col[i]->author, col[i]->page, col[i]->price);
free(col[i]);
}
}
Your original function signature only passes one pointer to the function when you need to pass an array of pointers.
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getting runtime error SIGTSTP on codechef, can't find whats wrong, when i compile and this code on my system it work upto for loop after that it stuck.
this is my code
#include <stdio.h>
struct invent
{
char *name[20];
int number;
float price;
};
int main()
{
struct invent product[3], *ptr;
printf("input\n\n");
for(ptr = product; ptr < product+3; ptr++)
scanf("%s %d %f", ptr->name, &ptr->number, &ptr->price);
printf("\nOutput\n\n");
for(ptr = product;ptr < product + 3; ptr++)
{
printf("%-20s %5d %10.2f\n", ptr->name, ptr->number, ptr->price);
}
return(0);
}
You should init the struct before you filled it , and use a table of char instead of table of pointer of char
#include <stdio.h>
#include <string.h>
struct invent
{
char name[20];
int number;
float price;
};
int main()
{
struct invent product[3], *ptr;
printf("input\n\n");
for(ptr = product; ptr < product+3; ptr++) {
memset(ptr, 0 , sizeof(*ptr));
scanf("%s %d %f", ptr->name, &ptr->number, &ptr->price);
printf("\nOutput\n\n");
}
for(ptr = product;ptr < product + 3; ptr++)
{
printf("%20s %5d %10.2f\n", ptr->name, ptr->number, ptr->price);
}
return(0);
}
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I want to store name id in a structure. then I want to print them. Condition is if there is no store data in structure print "No data". But I can't do this in if condition.
#include<stdio.h>
struct store
{
char name[100];
int id[50];
} info[100];
int main()
{
int i=0;
printf("Enter your name\n");
scanf("%s",info[i].name);
printf("Enter your ID\n");
scanf("%d",info[i].id);
if(info.name[i]!='\0')
{
printf("%s",info[i].name);
}
else
{
printf("No data found");
}
}
When you refer to an array by its name only, it decays into a pointer to its 1st element. So info.name will not compile, it would need to be info->name instead. However, everywhere other than your if statement, you are using info[i].name to access the name of a specific element at index i, which is fine, but then you use info.name[i] in the if statement, which is not fine. See the difference? To access the 1st char of a name of a specific element, you would need info[i].name[0] instead.
Also, you are declaring the id field as an array of ints, but you really only need 1 int.
Also, you are not initializing the info array before filling it with data.
Try something more like this instead:
#include <stdio.h>
#include <string.h>
struct store
{
char name[100];
int id;
} info[100];
int main()
{
memset(info, 0, sizeof(info));
int i = 0;
printf("Enter your name\n");
scanf("%99s", info[i].name);
printf("Enter your ID\n");
scanf("%d", &(info[i].id));
if (info[i].name[0] != '\0')
{
printf("%d %s", info[i].id, info[i].name);
}
else
{
printf("No data found");
}
}
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i am not getting output for this program.
// Pointer and structure
I want get output as 1Jatin. but for refreshing pointer by using structure. i cant do that. It working as int and float. but not as int and char. any one please solved out this.
#include <stdio.h>
struct name{
int a;
char b;
};
int main(){
struct name *ptr ,p;
ptr = &p;
printf("Enter integer:");
scanf("%d", &(*ptr).a);
printf("Enter name:");
scanf("%s", &(*ptr).b);
printf("Displaying:");
printf("%d%s",(*ptr).a,(*ptr).b);
return 0;
}
#include <stdio.h>
#define MAX_NAME_LENGTH 32
struct name{
int a;
char b[MAX_NAME_LENGTH];
};
int main(){
struct name *ptr ,p;
ptr = &p;
printf("Enter integer:");
scanf("%d", &ptr->a);
printf("Enter name:");
scanf("%s", ptr->b);
printf("Displaying: ");
printf("%d %s\n",ptr->a,ptr->b);
return 0;
}
Many things:
You can simply us -> operator to dereference pointer to its members
C-Strings are null terminated arrays of chars. That means that b member must be an array large enough to store a name characters + null terminator ('\0', 0x00, 0).
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I need to get result from __VA_ARGS to a function, and from there I need to pass string of each argument to a 2d character array.
If you are under C99, you can use compound literals
#include <stdio.h>
#define MACRO(...) func( \
sizeof((char *[]){__VA_ARGS__}) / sizeof(char *), \
(char *[]){__VA_ARGS__} \
)
void func(size_t n, char **p)
{
size_t i;
for (i = 0; i < n; i++) {
printf("%s\n", p[i]);
}
}
int main(void)
{
MACRO("abc", "def", "ghi");
return 0;
}
Notice that __VA_ARGS__ are evaluated twice in order to get the number of elements using sizeof, as an alternative you can send NULL as last parameter (sentinel):
#include <stdio.h>
#define macro(...) func((char *[]){__VA_ARGS__, NULL})
void func(char **p)
{
while (*p != NULL) {
printf("%s\n", *p);
p++;
}
}
int main(void)
{
macro("abc", "def", "ghi");
return 0;
}
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when i execute it the function do not work why?
#include<stdio.h>
struct stack{
int x[10];
int last;
};
void init(struct stack *s)
{
s->last=0;
}
void insert(struct stack *s)
{
int a;
while(a!=0)
{
int i;
printf("Enter the value\n");
scanf("%d",&i);
s->last++;
s->x[s->last]=i;
printf("%d",s->x[s->last]);
printf("enter 1 to continue 0 to exit\n");
scanf("%d",&a);
}
}
int main()
{
struct stack s;
int y,z;
printf("Trying out stacks\n");
printf("\n______________\n");
init(s);
insert(s);
return 0;
}
In function insert(), you declared
int a;
and then without initializing a you are doing the following,
while(a!=0)
will give Undefined Behaviour.
The following lines can leads buffer overflow,
s->last++;
s->x[s->last]=i; // no restriction applied on last
last can be more than 9 which can cause buffer overflow as x[10].