I try to make a recursive program but it's doesn't work.
the program to count number in teks.
example :
input:
abcde1234
and
output :
4
this my code :
#include<stdio.h>
int count_digits(char s[]);
int main (){
char x[1000];
printf("input string (max 1000 character): ");
scanf("%s", &x);
printf("number of digits in the text = %i", count_digits(x));
return 0;
}
int count_digits(char s[]){
int j, digits=0;
for (j=0; s[j] !='0'; j++)
{
if(s[j] >= '0' && s[j] <= '9'
{
digits++;
}
}
}
maybe anyone can help me to fixed it :) . my program still show output = 9 not 4.
You have to return the calculated value. Add in the end of your function:
return digits;
By the way, you program in not written in recursive approach.
should be something like:
int count_digits(char s[]){
if (!*s)
return 0;
return (*s >= '0' && *s <= '9') + count_digits(s+1);
}
scanf("%s", &x); invokes undefined behavior by passing data having wrong type. The & should be removed.
The loop condition s[j] !='0' is wrong. It should be s[j] !='\0' to stop at the terminating null-character.
You forgot to add ) at the end of if line.
You forgot to return the result digits from the function count_digits.
Try this:
#include<stdio.h>
int count_digits(char s[]);
int main (){
char x[1000];
printf("input string (max 1000 character): ");
scanf("%s", x); /* remove extra & */
printf("number of digits in the text = %i", count_digits(x));
return 0;
}
int count_digits(char s[]){
int j, digits=0;
for (j=0; s[j] !='\0'; j++)
{
if(s[j] >= '0' && s[j] <= '9') /* add ) */
{
digits++;
}
}
return digits; /* return the result */
}
Then, try to make the recursive version!
Related
As stated in the title I am trying to find all lower-case letters that are not in a series of words. There are no upper-case letters, digits, punctuation, or special symbols.
I need help fixing my code. I am stuck and do not know where to go from here.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main(void){
int letters[26];
char words[50];
int i = 0, b = 0;
printf("Enter your input : ");
scanf("%s", words);
for(i = 0; i < 26; i++){
letters[i] = 0;
}
while(!feof(stdin)){
for(b = 0; b < strlen(words) - 1; b++){
letters[ words[b] - 'a']++;
scanf("%s", words);
}
}
printf("\nMissing letters : %c ", b + 97);
return 0;
}
My output is giving me some random letter that I do not know where it is coming from.
Here is a working first implementation.
As well as the comments that have already been made, you should use functions wherever possible to separate out the functionality of the program into logical steps. Your main function should then just call the appropriate functions in order to solve the problem. Each function should be something that is self contained and testable.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define MAX_INPUT 20 /* Max input to read from user. */
char *readinput(void);
void find_missing_lower_case(char *, int);
int main()
{
char *user_input = readinput();
int len_input = strlen(user_input);
printf("user input: %s\n", user_input);
printf("len input: %d\n", len_input);
find_missing_lower_case(user_input, len_input);
/* Free the memory allocated for 'user_input'. */
free(user_input);
return 0;
}
char *readinput()
{
char a;
char *result = (char *) malloc(MAX_INPUT);
int i;
for(i = 0; i < MAX_INPUT; ++i)
{
scanf("%c", &a);
if( a == '\n')
{
break;
}
*(result + i) = a;
}
*(result + i) = '\0';
return result;
}
void find_missing_lower_case(char *input, int len_input)
{
int a = 97; /* ASCII value of 'a' */
int z = 122; /* ASCII value of 'z' */
int lower_case_chars[26] = {0}; /* Initialise all to value of 0 */
/* Scan through input and if a lower case char is found, set the
* corresponding index of lower_case_chars to 1
*/
for(int i = 0; i < len_input; i++)
{
char c = *(input + i);
if(c >= a && c <= z)
{
lower_case_chars[c - a] = 1;
}
}
/* Iterate through lower_case_chars and print any values that were not set
* to 1 in the above for loop.
*/
printf("Missing lower case characters:\n");
for(int i = 0; i < 26; i++)
{
if(!lower_case_chars[i])
{
printf("%c ", i + a);
}
}
printf("\n");
}
I figured it out and this is the code I used.
int main(void)
{
int array[26];
char w;
int i=0;
for(i=0; i<26; i++) {
array[i]=0; }
printf("Enter your input: ");
scanf("%c", &w);
while(!feof(stdin)) {
array[w-97] = 1;
scanf("%c", &w); }
printf("Missing letters: ");
for(i=0; i<26; i++) {
if(array[i] == 0) {
printf("%c ", i+97); }
}
printf("\n");
return 0;
}
I want to do a program that ask to the user to give one character, then enter... until he wants to stop by pressing enter and no caracters.
Then, the program will say: "you gave the caracters ...."
for example:
give the caracter 1: k + enter
give the caracter 2: l + enter
give the caracter 3: just enter ('\n')
result: You gave the caracters: kl
My code doesnet work because when i just press enter, nothing happen. Here is the code:
#include <stdio.h>
#define N 1000
int main() {
int i = 0;
int j = 0;
char str[N];
while (str[i] != '\n') {
printf("element number str[%d] : ", i);
scanf("%s", &str[i]);
i++;
}
printf("The string is: ");
while (j < i) {
printf("%s", str[j]);
j += 1;
}
return 0;
}
You can do it with c = getchar(); or c = fgetc(stdin) function:
#include <stdio.h>
#define N 1000
int
main ()
{
int i = 0;
int j = 0;
int c;
char str[N];
while (1)
{
c = fgetc(stdin); // or c = getchar();
if ( (c != EOF) && (c != 0x0A ) ) // 0x0A = 'nl' character
{
str[i] = (char) c;
printf ("element number str[%d]=%c \n", i, str[i++] );
}
else
{
str[i] = 0;
break;
}
}
printf ("The string is: %s", str);
return 0;
}
OUTPUT:
This is my string!
element number str[1]=T
element number str[2]=h
element number str[3]=i
element number str[4]=s
element number str[5]=
element number str[6]=i
element number str[7]=s
element number str[8]=
element number str[9]=m
element number str[10]=y
element number str[11]=
element number str[12]=s
element number str[13]=t
element number str[14]=r
element number str[15]=i
element number str[16]=n
element number str[17]=g
element number str[18]=!
The string is: This is my string!
Or you can use your original scanf("%s", &str1);
#include <stdio.h>
#define N 1000
int main ()
{
int i = 0;
int k = 0;
int c;
int len;
char str[N];
char str1[N];
scanf("%s", &str1);
len = strlen(str1);
for(k = 0; k < len; k++)
{
c = str1[k];
if ( (c != EOF) && c != '\n') // EOF will work for ^D on UNIX
{
str[i] = (char) c;
printf ("element number str[%d]=%c \n", i, str[i++] );
}
else
{
str[i] = 0;
break;
}
}
printf ("The string is: %s", str);
return 0;
}
OUTPUT:
12345
element number str[1]=1
element number str[2]=2
element number str[3]=3
element number str[4]=4
element number str[5]=5
The string is: 12345
As stated in this answer scanf will not return until you give it a string, i.e. it skips whitespace.
As suggested in the answer and in general, using fgets is the better option.
Edit: A way to accomplish what you want would look like this:
#include <stdio.h>
#define N 1000
int main() {
int i = 0;
int j = 0;
char str[N];
do {
printf("element number str[%d] : ", i);
fgets(&str[i], 3, stdin);
i++;
} while (str[i - 1] != '\n');
printf("The string is: ");
while (i > j) {
printf("%c", str[j]);
j++;
}
return 0;
}
In the fgets you use the number 3 because pressing enter gives both a newline character [/n] and a return carriage [/r].
//Program to find max occurring character in string
#include<stdio.h>
#include<conio.h>
#define MAX_SIZE 100 // Maximum string size, change to make string smaller or larger
#define MAX_CHARS 255 // Maximum characters allowed for characters
void main()
{
char str[MAX_SIZE]; //store the string
int freq[MAX_CHARS]; // store frequency of each character
int i, max; // i is for loop max to store frequency
int ascii; //stores ascii value convertd from each char
char ch; //for choice
do{
clrscr();
i=0;
printf("\nEnter any string: ");
gets(str);
// Initializes frequency of all characters to 0
for(i=0; i<MAX_CHARS; i++)
{
freq[i] = 0;
}
// Finds occurance/frequency of each characters
i=0;
while(str[i] != '\0')
{
ascii = (int)str[i];
freq[ascii] += 1; //string's element is casted to int to store its ascii value for further comparision
i++;
}
// Finds maximum frequency of character
max = 0;
for(i=0; i<MAX_CHARS; i++)
{
if(freq[i] > freq[max])
max = i; //to print no. of times
}
printf("\nMaximum occurring character is '%c' = %d times.", max, freq[max]);
printf("\n Want to find again??(y/n):");
scanf("%c",&ch);
}while(ch=='Y'||ch=='y');
}
When I give it the input: "aaaaeeee", the output is "a" occurring 4 times, but "e" occurs 4 times too. I know this is sorted by ascii values and thats why it gives "a" as output, but what can I do in this program that the output gives both "a" and "e" as output when a case like this occurs?
Add max calculation ahead
i = 0;
max = 0;
while(str[i] != '\0')
{
ascii = (int)str[i];
freq[ascii] += 1;
if (freq[ascii] > max) max = freq[ascii]; // <==== here
i++;
}
Note that this is the max number of the same character you might have.
Then display all chars which maximum is equal to max
for(i=0; i<MAX_CHARS; i++)
{
if(freq[i] == max) printf("Character %c is at max %d\n", i, max);
}
To fix the endless loop, before the while add char c ; while ((c = getchar()) != EOF && c != '\n');
scanf("%c",&ch);
char c;
while ((c = getchar()) != EOF && c != '\n'); // <== note the ';'
} while(ch=='Y'||ch=='y');
Note that you shouldn't use gets, reason is explained here.
Whole code:
void main()
{
char str[MAX_SIZE]; //store the string
int freq[MAX_CHARS]; // store frequency of each character
int i, max; // i is for loop max to store frequency
int ascii; //stores ascii value convertd from each char
char ch; //for choice
do {
printf("\nEnter any string: ");
gets(str);
// Initializes frequency of all characters to 0
for(i=0; i<MAX_CHARS; i++)
{
freq[i] = 0;
}
// Finds occurance/frequency of each characters
for(i=0,max=0 ; str[i] != '\0' ; i++)
{
ascii = (int)str[i];
freq[ascii] += 1; //string's element is casted to int to store its ascii value for further comparision
if (freq[ascii] > max) max = freq[ascii];
}
for(i=0; i<MAX_CHARS; i++)
{
if(freq[i] == max) printf("Character %c is at max %d\n", i, max);
}
printf("\n Want to find again??(y/n):");
scanf("%c",&ch);
char c;
while ((c = getchar()) != EOF && c != '\n');
}while(ch=='Y'||ch=='y');
}
Above this line
printf("\nMaximum occurring character is '%c' = %d times.", max, freq[max]);
Delete it and add this code
for(i=0;i<MAX_CHARS;i++)
{
if(freq[i]==freq[max])
{
printf("\nMaximum occurring character is '%c' = %d times.", i, freq[i]);
}
}
I'm having trouble outputting an invalid statement if the user inputs a letter instead of a number into a 2D array.
I tried using the isalpha function to check if the input is a number or a letter, but it gives me a segmentation fault. Not sure what's wrong any tips?
the following code is just the part that assigns the elements of the matrix.
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#define MAX 10
void display(int matrix[][MAX], int size);
int main() {
int n, degree;
int matrix[MAX][MAX];
printf("Enter the size of the matrix: "); // assigning size of the matrix
scanf("%d", &n);
if (n <= 1 || n >= 11) { // can't be bigger than a 10x10 matrix
printf("Invalid input.");
return 0;
}
for (int i = 0; i < n; ++i) { // assigning the elements of matrix
printf("Enter the row %d of the matrix: ", i);
for (int j = 0; j < n; ++j) {
scanf("%d", &matrix[i][j]);
if (!isalpha(matrix[i][j])) { // portion I'm having trouble with
continue;
} else {
printf("Invalid input.");
return 0;
}
}
}
...
As the value of n will be number, we can solve it using string instead of int.
char num[10];
int n;
scanf("%s", num);
if(num[0] < '0' || num[0] > '9' || strlen(num) > 2){
printf("invalid\n");
}
if(strlen(num) == 1) n = num[0] - '0';
if(strlen(num) == 2 && num[0] != 1 && num[1] != 0) printf("invalid\n");
else n = 10;
Also we can use strtol() function to convert the input string to number and then check for validity.You can check the following code for it. I have skipped the string input part. Also you have to add #include<stdlib.h> at the start for the strtol() function to work.
char *check;
long val = strtol (num, &check, 10);
if ((next == num) || (*check != '\0')) {
printf ("invalid\n");
}
if(val > 10 || val < 0) printf("invalid\n");
n = (int)val; //typecasting as strtol return long
You must check the return value of scanf(): It will tell you if the input was correctly converted according to the format string. scanf() returns the number of successful conversions, which should be 1 in your case. If the user types a letter, scanf() will return 0 and the target value will be left uninitialized. Detecting this situation and either aborting or restarting input is the callers responsibility.
Here is a modified version of your code that illustrates both possibilities:
#include <stdio.h>
#define MAX 10
void display(int matrix[][MAX], int size);
int main(void) {
int n, degree;
int matrix[MAX][MAX];
printf("Enter the size of the matrix: "); // assigning size of the matrix
if (scanf("%d", &n) != 1 || n < 2 || n > 10) {
// can't be bigger than a 10x10 matrix nor smaller than 2x2
// aborting on invalid input
printf("Invalid input.");
return 1;
}
for (int i = 0; i < n; i++) { // assigning the elements of matrix
printf("Enter the row %d of the matrix: ", i);
for (int j = 0; j < n; j++) {
if (scanf("%d", &matrix[i][j]) != 1) {
// restarting on invalid input
int c;
while ((c = getchar()) != '\n') {
if (c == EOF) {
printf("unexpected end of file\n");
return 1;
}
}
printf("invalid input, try again.\n");
j--;
}
}
}
...
The isdigit() library function of stdlib in c can be used to check if the condition can be checked.
Try this:
if (isalpha (matrix[i][j])) {
printf ("Invalid input.");
return 0;
}
So if anyone in the future wants to know what I did. here is the code I used to fix the if statement. I am not expecting to put any elements greater than 10000 so if a letter or punctuation is inputted the number generated will be larger than this number. Hence the if (matrix[i][j] > 10000). May not be the fanciest way to do this, but it works and it's simple.
for (int i = 0; i < n; ++i) { // assigning the elements of matrix
printf("Enter the row %d of the matrix: ", i);
for (int j = 0; j < n; ++j) {
scanf("%d", &matrix[i][j]);
if (matrix[i][j] > 10000) { // portion "fixed"
printf("Invlaid input");
return 0;
}
}
}
I used a print statement to check the outputs of several letter and character inputs. The lowest out put is around and above 30000. So 10000 I think is a safe condition.
So I am trying to make a infix to postfix program in C but when I start entering the symbols, the loop ends at the first entry.
I am pretty sure it's a data type problem somewhere but I can't figure out where..
Here is the code:
#include <stdio.h>
#include <stdlib.h>
static int N;
static char *s;
void stackinit(int max){
s = malloc(max*sizeof(int));
N = 0;
}
int stackempty(){
if(N==0)
return(1);
else
return(0);
}
void stackpush(char item){
s[N] += item;
N++;
}
int stackpop(){
N--;
return(s[N]);
}
int priority(char x){
if(x == '+' || x == '-')
return(0);
if(x == '*' || x == '/')
return(1);
}
int main(void){
int i,sum;
char input;
printf("Infix to Postfix\n");
printf("How many characters will you enter?");
scanf("%d", &sum);
stackinit(sum);
for(i = 0; i < sum; i++){
printf("Enter character: ");
scanf("%s", &input);
stackpush(input);
}
while(!stackempty()){
printf("%d ", stackpop());
}
/*for(i = 0; i < sum; i++){
}*/
}
scanf() uses %c to reading characters, so your code should be
scanf(" %c", &input);
By adding a space after your %c specifier, you also consume any new line or space characters that might be added unintendedly, then correcting your loop issue.
As another thought, you will need to append an extra character onto your string: a null character, which is a '\0' character. This is why you will need to do s = malloc(max*sizeof(int) + 1);, so that you have space left for your '\0', which, in your case, you can add dynamically on your stackPush() function, like that:
void stackpush(char item){
s[N++] = item;
s[N] = '\0';
}
Also, in your stackPush function, what you want is s[N] = item;, not s[N] += item;
More on C Strings