first time posting and also a beginner of C. My problem is how do I print an unkown number of results? Take this code for example:
#include <stdio.h>
int main(void)
{
int a,b,c;
b=0;
printf("Enter the number of terms: ");
scanf("%d", &a);
for(b=0; b<=a; ++a)
{
printf("\n\nEnter the value of each term: ");
scanf("%d",&c);
}
printf("\n\n%d",c);
return(0);
}
I want to print all the values entered in the end but Idk how to adjust it so that it will print 1,2,etc values.
P.S. How can I do this in a while loop as well using fprintf.
You will want to use what is called an Array to store your data. You can think of an Array sort of like a filing cabinet with different drawers. Each drawer can store a value, and you can access that drawer by referencing its index.
You can learn all about arrays in C here:
http://www.thegeekstuff.com/2011/12/c-arrays/
Good luck!
Edit: Here is an example of fprintf:
/* fprintf example */
#include <stdio.h>
int main ()
{
FILE * pFile;
int n;
char name [100];
pFile = fopen ("myfile.txt","w");
for (n=0 ; n<3 ; n++)
{
puts ("please, enter a name: ");
gets (name);
fprintf (pFile, "Name %d [%-10.10s]\n",n,name);
}
fclose (pFile);
return 0;
}
Related
for(int i=0;i<num; i++)
{
char word[32];
scanf(" %[^\n]s",word);
makeDictionary(word, readDictionary);
}
I have a program where I want to ask user for certain strings n times (with spacing allowed). However, when they input for example n = 2, it only loops once and exists. I know there is something wrong with my scanf.
I do Java and I'm a beginner at C. The way strings are done is very different.
This code can help you:
#include <stdio.h>
#include <string.h>
int main()
{
int N;
do
{
printf("Give me number of words :");
scanf("%d",&N);
}while(N<1);
for(int i=0;i<N;i++)
{char str[20];
printf("\nGive me the %d word :",i+1);
scanf("%s[^\n]",str);
printf("%s",str);
}
}
I create it a program that asks for raw and columns after that asks you to put numbers to the dimensional array. This arrays inputs to a file. When i open the file i can't see the array.
#include <stdio.h>
#include <stdlib.h>
#include <curses.h>
int main () {
FILE *fp;
int n,m;
int i,j;
float b;
char filename[100];
int getfloat(float *);
printf("Number of rows\n");
scanf("%d",&n);
printf("Number of colums\n");
scanf("%d",&m);
float s[n][m];
for (i=1;i<=n;i++)
{
for (j=1;j<=m;++j)
{
printf("Insert number %d",i);
printf(",%d\n", j);
scanf("%f",&b);
s[i][j]=b;
}
}
printf("Enter file name \n");
scanf("%s", filename);
// ****print file****
fp=fopen(filename,"w+");
if(fp!=NULL)
{
fputs(s,fp);
fprintf("%c",s);
}
fclose(fp);
return 0;
the only thing i see is this
If you want a list of numbers, probably in some kind of grid in the file, then at the minimum you want a loop such as the following:
for (int i=0; i<n; ++i)
{
for (int j=0; j<m; ++j)
{
fprintf(fp, "%f ", s[i][j]);
}
fprintf(fp, "\n");
}
See fprintf for documentation on the format specifiers; you'll probably want to tweak that to get better-looking values.
Also, again, note that arrays start from 0. Your initial read loop skips the very first element, and writes past the end of the actual array.
fprintf("%c", s); and fputs does not print out the contents of the array, it prints out the location stored in the array's pointer and tries to interpret it as a char. What you would need to print out the proper values is to loop through each value and use fprintf with each float value, using s[i][j] similar to how you initialized it.
The way you initialized the array is also off, as arrays begin at 0, not 1. Currently your for loop does not ever access s[0][0] or s[1][0] and so on. Your for loops should have i initialized to 0, and have the condition be i < n instead of i<=n.
I know that I can use
scanf("%d %d %d",&a,&b,&c):
But what if the user first determines how many input there'd be in the line?
You are reading the number of inputs and then repeatedly (in a loop) read each input, eg:
#include <stdio.h>
#include <stdlib.h>
int main(int ac, char **av)
{
int numInputs;
int *input;
printf("Total number of inputs: ");
scanf("%d", &numInputs);
input = malloc(numInputs * sizeof(int));
for (int i=0; i < numInputs; i++)
{
printf("Input #%d: ", i+1);
scanf("%d", &input[i]);
}
// Do Stuff, for example print them:
for (int i=0; i < numInputs; i++)
{
printf("Input #%d = %d\n", i+1, input[i]);
}
free(input);
}
Read in the whole line, then use a loop to parse out what you need.
To get you started:
1) Here is the manual page for getline(3):
http://man7.org/linux/man-pages/man3/getline.3.html
2) Some alternatves to getline:
How to read a line from the console in C?
3) Consider compressing spaces:
How do I replace multiple spaces with a single space?
4) Use a loop for parsing. You might consider tokenizing:
Tokenizing strings in C
5) Be careful and remember that your user could enter anything.
#include <conio.h>
#include <stdio.h>
main()
{
int a[100],i,n_input,inputs;
printf("Enter the number of inputs");
scanf("%d",&n_input);
for(i=0;i<n_input;i++)
{
printf("Input #%d: ",i+1);
scanf("%d",&a[i]);
}
for(i=0;i<n_input;i++)
{
printf("\nInput #%d: %d ",i+1,a[i]);
}
}
/*
_______________This program is in C Programming Language_______________
We have to directly enter all the elements in one line giving spaces between them. Compiler will automatically ends the for loop I have used and assign the value to their respective variables or array indexes. Below program and output will give you better understanding.
*/
#include <stdio.h>
int main()
{
//taking no of inputs from user
int len;
printf("Enter the number of inputs you want to enter : ");
scanf("%d", &len);
int i;
//defined an array for storing multiple outputs
int arr[100];
//included a printf statement for better understanding of end user
printf("Enter the inputs here by giving space after each input : ");
/*here is the important lines of codess for taking multiple inputs on one line*/
for (i=0;i<len;i++)
{
scanf("%d", &arr[i]);
}
printf("Your entered elements is : ");
for (i=0;i<len;i++)
{
printf("%d ", arr[i]);
}
}
/*
OUTPUT :
Enter the number of inputs you want to enter : 5
5 5 5 8 7
Your entered elements is : 5 5 5 8 7
*/
#include <stdio.h>
#include <stdlib.h>
struct the_struct
{
char FirstName[20];
char LastName[32];
int Score[20];
};
int main ()
{
int i,n;
struct the_struct *ptr[100];
printf("how many students?\n");
scanf("%d",&n);
while (i<=n);
{
i==0;
ptr[i] = malloc(sizeof(struct the_struct));
printf("Enter First Name \n");
scanf("%s",ptr[i]->FirstName);
printf("Enter Last Name \n");
scanf("%s",ptr[i]->LastName);
printf("Enter Score? \n");
scanf("%s",ptr[i]->Score);
printf("%s %s %s\n",ptr[i]->FirstName,ptr[i]->LastName,ptr[i]->Score);
i++;
}
}
hey guys, so when i enter the first input, it goes only once without going on for the number the user inputs, i tried the for loop but same result.
still learning C so my apology if i misunderstood something.
Thanks in advance.
Your while loop is problematic. You could rewrite it as:
for (i = 0; i < n; ++i)
{
ptr[i] = malloc(sizeof(struct the_struct));
printf("Enter First Name \n");
scanf("%s",ptr[i]->FirstName);
printf("Enter Last Name \n");
scanf("%s",ptr[i]->LastName);
printf("Enter Score? \n");
scanf("%s",ptr[i]->Score);
printf("%s %s %s\n",ptr[i]->FirstName,ptr[i]->LastName,ptr[i]->Score);
}
And since you use %s to read and print Score, you should declare it as char Score[20]; instead of int.
The problem is that i is uninitialized. Therefore, the loop while (i <= n) has undefined behavior, and can end at any time.
Add int i = 0 initializer to fix this problem.
Notes:
i == 0 expression at the beginning of the loop has no effect
Since i starts at zero, your while loop should be while (i < n), not <=.
You should check the results of scanf to see if the user entered something meaningful
You should specify the size of the array into which you read a string, e.g. scanf("%31s",ptr[i]->LastName); This prevents buffer overruns.
I have to write a function which checks if a value is located in an array with N elements using for loop.I wrote the code
#include <stdio.h>
int main ()
int N[100],n,i;
printf ("Write the value of n:");
scanf ("%d",&n);
i=0;
printf ("Write the value of the element :");
scanf ("%d",&v[i]);
for (i=0,i<n,i++)
{
if (N[i]==n)
}
printf ("The value is located in the array :");
return 0;
When I compile it,it says syntax error before printf.What does this mean?What have I done wrong?
Basic syntax issues. Try:
#include <stdio.h>
int main(void)
{
int N[100],n,i;
printf ("Write the value of n:");
scanf ("%d",&n);
i=0;
printf("Write the value of the element :");
scanf("%d", &v[i]); /* v doesn't exist */
/* you are looping up to n, which could be anything */
for (i=0; i<n; i++)
{
/* you never populate N, so why would you expect n to be found?
the value of any element in N is indeterminate at this point */
if (N[i]==n)
{
printf ("The value is located in the array :");
}
}
return 0;
}
That said, you have logical problems here:
v is not declared anywhere.
You never populate your array (N).
n is a value entered by the user, not the upper bound of the array. What if I enter 101?
Those are more than syntax issues, you'll need to fix your logic.