Working on Ubuntu
I have a problem with my code and i dont know how to fix. Maybe there is a function that will help me with that.
I want to input a string and then my program need to check if it is a number from 1 to 1000. If there is a letter or a symbol
Here is my code:
char tab[200]="";
int i;
scanf("%199[^\n]s",tab);
for(i=0;i<200;i++)
{
if(tab[i] >= 'A' && tab[i]<='Z')
{
printf("Big letters\n");
}
else if(tab[i] >= 'a' && tab[i]<='z')
{
printf("Small letters\n");
}
}
if(strlen(tab) == 4 && tab[3] > 0 && tab[2] > 0 && tab[1] > 0 && tab[0] > 1)
{
printf("Bigger then 1k\n");
}
else if(strlen(tab) > 4)
{
printf("Longer then 4 chars\n");
}
It's not working properly and it also doesnt include symbols...
I've found code like this but im not sure how to make my number less then 1001
char input[MAXINPUT] = "";
int length,i;
int number;
printf(" id: \n");
fgets(input, MAXINPUT, stdin);
number = atoi(input);
length = strlen (input);
for (i=0;i<length; i++)
if (!isdigit(input[i]))
{
printf ("Entered input is not a number\n");
exit(1);
} else if (number < 1001)
printf ("Given input is a number\n");
Not sure if i am using fgets properly here.
Before u will send me to here
, please read my question
Use This.. Maybe This Help. You can Modify it on your Choice.
#include<string.h> // header file for strlen()
void method()
{
char tab[200]="";
int i;
scanf("%199[^\n]s",tab);
for(i=0;i<strlen(tab);i++) // Loops only to the lenght of total vlaues in array
{
if(tab[i] >= 65 && tab[i]<=90) // Ascii Value of Capital Ltrs
{
printf("Big letter\n");
}
else if(tab[i] >= 97 && tab[i]<=122) // Ascii Value of Small Ltrs
{
printf("Small letter\n");
}
else if(tab[i] >= 48 && tab[i]<=57) // Ascii Value of Numbers
{
printf("Number\n");
}else // of else other numebrs are all Symbols but can be
{
printf("Symbols\n");
}
}
}
Please note that you're compareing characters with integers (numbers). The character '1' in ascii is 49, as an example, while you have been using the numeric value 1 in the comaprisons. Test to add single quotation marks similar to those around your letter comparisons and see if you don't get a different result.
Best regards
Esbjörn
Related
I have a problem that needs to calculate the grade needed on a final exam in order to get the letter grade that they desire. I have the code correct for the calculations but I need to account for all invalid user input. I have accounted for negative grades and letter grades that don't exist but I can't figure out how to make sure the percentages they are inputting don't contain letters or other characters. For example if I ask for their current grade in the class they cannot input something like 95.6asi!. This is the code I have right now but there are many errors.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
void calcGradeNeededOnFinal() {
double percentWanted = 0.0;
double currentGrade, finalWeight;
char gradeWanted;
printf("Enter the grade you want in the class: ");
scanf("%c", &gradeWanted);
if (gradeWanted == 'A' || gradeWanted == 'a'){
percentWanted = 90.0;
}
else if (gradeWanted == 'B' || gradeWanted == 'b'){
percentWanted = 80.0;
}
else if (gradeWanted == 'C' || gradeWanted == 'c'){
percentWanted = 70.0;
}
else if (gradeWanted == 'D' || gradeWanted == 'd'){
percentWanted = 60.0;
}
else if (gradeWanted == 'F' || gradeWanted == 'f'){
percentWanted = 0.0;
}
else {
printf("Unknown Grade Received: %c. Ending Program.\n", gradeWanted);
exit(0);
}
printf("Enter your current percent in the class: ");
scanf("%lf", ¤tGrade);
if(currentGrade < 0) {
printf("The number you last entered should have been positive. Ending program.\n");
exit(0);
}
char gradeString = (char)currentGrade;
for(int i=0; i < strlen(gradeString); ++i) {
if(!(isdigit(gradeString[i])) && (strcmp(gradeString[i], '.') != 0))) {
printf("Invalid formatting. Ending program.\n");
exit(0);
}
}
printf("Enter the weight of the final: ");
scanf("%lf", &finalWeight);
if(finalWeight < 0) {
printf("The number you last entered should have been positive. Ending program.\n");
exit(0);
}
char weightString = (char)finalWeight;
for(int i=0; i < strlen(weightString); ++i) {
if(!(isdigit(weightString[i])) && (strcmp(weightString[i], '.') != 0))) {
printf("Invalid formatting. Ending program.\n");
exit(0);
}
}
// this calculates the grade need on the final test to get the desired grade of the user
double gradeNeededOnFinal = (percentWanted - (currentGrade * (1.0 - finalWeight/100.0))) / (finalWeight/100.0);
printf("You need to get at least %.2lf%% on the final to get a %c in the class.\n", gradeNeededOnFinal, gradeWanted);
}
int main() {
calcGradeNeededOnFinal();
return 0;
}
For example if I ask for their current grade in the class they cannot input something like 95.6asi!.
You have declared grade as char so there is no possibility that it can store 95.6asi!
char gradeWanted;
What you need is : isalpha or isupper and islower function(s) from ctype.h
isalpha() checks for an alphabetic character; in the standard "C" locale, it is equivalent to (isupper(c) || islower(c)). In some locales, there may be additional characters for which isalpha() is true-letters which are neither upper case nor lower case.
Just check if your gradeWanted is an alphabet or not.
Using
if (isalpha( gradeWanted ))
or
if (isupper( gradeWanted ) || islower( gradeWanted ))
is enough.
All ctype functions takes an int and returns an int, you can declare char gradeWanted; as int gradeWanted;
you could read the characters entered and, using the ascii encoding, check (perhaps with a switch) which character is inserted and manage it.
This way you have full control of the entries.
you can get char to ascii conversion with:
int a_as_int = (int)'a';
First, I apologize if the question doesn't make sense as my English isn't that good...
My question is, how do we print out different things depending on the user input?
What I'm trying to do is: when user inputs integer, the program prints out the inputted number. When the user inputs something that's not integer (like symbols and characters), the program prints out "not integer".
my current idea (pseudo-code) is as follows:
`int main(){
int value;
printf("Enter numbers");
scanf("%d", &value);
if(value is integer){
printf("%d", value);
} else {
printf("not integer");
}
return 0;
}`
what gets me is the scanf; by using %d, I'm assuming that the user will input an integer values, but the user can input values that are not integers so I can't make a comparison using the if statement if( value is integer). How can I make a comparison that will determine whether the inputted value is integer or not?
I don't know if this is a good thing or not.
You can use ASCII to check if the input type is an integer or not
(between 48 - 57 in ASCII)
it will be like this
char value;
int flag = 0; //to check true or false (0 means false, and 1 means true)
printf("Enter numbers");
scanf("%c", &value);
for(int i = 48; i <= 57; i++){
if(value == i){
flag = 1;
break;
}
}
if(flag == 1){
printf("%c", value);
} else {
printf("not integer");
}
How do you print different things depending the user input?
Step 1: Read the line of user input
char buf[100];
if (fget(buf, sizeof buf, stdin)) {
// something was entered
Step 2: test the string
char *end;
long value = strtol(buf, *end);
// If the end is the same as the beginning, no conversion occurred.
if (end == buf) {
puts("not integer");
}
printf("%ld\n", value);
}
}
Additional code could look for input that occurred after the integer. Also code could test for a large number that overflowed the long range.
The code is as follows. It caters for different situations like inputting negative numbers and decimal numbers:
#include <stdio.h>
#include <string.h>
#include <ctype.h>
int main() {
char input[20];
int wrongFlag = 0;
scanf("%s", input);
if (input[0] == '0' && strlen(input) > 1) {
wrongFlag = 1;
//for number starts with 0, and string length>1 eg: 010
}
for (int i = 0; i < strlen(input); i++) {
if (i == 0 && (input[i] == '-' && strlen(input) > 2 && input[i + 1] == '0')) {
//check first round only: negative number with length >2 and starts with 0 eg: -010.
wrongFlag = 1;
continue;
}
if (i != 0 && !isdigit(input[i])) {
//check following rounds, check if it is not digit
wrongFlag = 1;
break;
}
}
if (wrongFlag) {
printf("Not integer");
}
else {
printf("integer");
}
return 0;
}
Try this it works for me.
#include<stdio.h>
#include<string.h>
int main()
{
int i;
char value[50];
int len;
printf("Enter maximum 50 digits\n");
/* enter the values you wanted*/
printf("Enter the value: ");
gets(value);
len = strlen(value);
/*it will iterate upto the end of the user input*/
for(i=0;i<len;i++)
{
if(48<value[i] && value[i]<=57)
{
if(i==(len-1))
printf("It's an integer");
}
else{
printf(" Not an integer");
break;
}
}
return 0;
}
Hey guys im trying to write a small program where the user has to put in a number between 1-9, anything else is an error, but I'm having trouble validating the input because if you put 12 it only reads the 1 and it goes in the loop. It has to be done using getchar() this is what have so far:
printf(%s,"please enter a number between 1 - 9);
int c;
c = getchar();
while(c != '\n') {
int count = 1;
count ++;
if ((c >= '0' && c <= '9') || count > 1) {
printf(%s, "Congrats!);
}
else
{
print(%s, "ERROR);
}
}
I'm also having problems validating the char into an int after it goes in. If i put in 5 i get 53.
Try changing count > 1 to count == 1, and initialize it to 0 rather than 1. That way you can keep count of the number of digits you have. Also, note that because you initialize count to 1 and then immediately increment it, count > 1 will always evaluate to true, so if you gave it any char it will always say it's correct.
getchar() will return the next character typed. If you want more than the first character you will need a call getchar() again within the while loop.
//Somewhere to store the result
//initialized with an invalid result value
int digitchar = 0;
//Get the first char
int c = getchar();
while (c != '\n')
{
//Check if we already have a digit
//and that the new char is a digit
if (digitchar == 0 && c >= '1' && c <= '9')
{
digitchar = c;
}
//Get the next char
c = getchar();
}
//Check if we have stored a result
if (digitchar != 0)
{
//Success
}
Note this doesn't handle if a non-digit or newline character is entered. You would need to handle that as an error as well as if more than one digit is entered.
This is not working with 12 because getchar() takes one character per time.The following example is one way to solve it.
printf("please enter a number between 1 - 9");
int c[10], count=1;
//Declare an array because user may insert a bigger number
char number;
//This loop allow the user to enter an input
for(i=0;i<10;i++){
number = getchar();
if (number != ' '){
c[i] = atoi(number);
sum = sum + c[i];
}
else if(number == ' '){
//Terminate the loop when user stop typing
break;
}
else if( sum > 9 || sum < 0){
//Start loop again until user enter valid input
printf("You entered a number out of field try again\n");
continue;
}
}
while(c != '\n') {
count ++;
if ((c >= '0' && c <= '9') || count > 1) {
printf("%d Congrats!",c);
}
else
{
printf(" %d ERROR", c);
}
}
Remember that getchar() returns the ascii value of the char, thus when you pass the value to the function you must subtract char '0' to pass the actual decimal value into the function.
Another point is that you must clear the input buffer. If your user enters wrong input, you have to make sure that there is nothing left on the input buffer before you try to read input again.
Hope this helps.
int main(void) {
int input = 0; // 0 is the sentinel value to close program
printf("\n%s\n", "Enter value between 1-9 .\nEnter [0] to finish.");
do {
input = getchar();
if (((input>= '1') && (input <= '9') || input == '0') && getchar() == '\n') {
if ((input >= '1') && (input <= '9')) {
callYourOwnFuntionAndPassValue(input - '0');
printf("\n%s\n", "Enter value between 1-9 .\nEnter [0] to finish.");
}
}
else {
while (getchar() != '\n') {} // clear input buffer
printf("\n%s\n", "Please enter a valid number");
}
} while (input != END_PROGRAM);
return NO_ERROR; // NO_ERROR = 0
}
I'm just a beginner and I'm trying to use whatever I know to make a simple program that:
Asks the user to input the letter 'S' or 's'. The program loops if 's' is not input. If the user does input 's', the program then
Asks the user to input a number, 1 or 2. The program loops if the incorrect number is input.
The problem I'm having is that after 's' is successfully input and the user is asked to enter a number, if an incorrect number is input (not 1 or 2) the program asks the user to input a letter again from the beginning which is incorrect. The program loops from the very beginning and doesn't work anymore. Can anyone help me fix this please?
#include <stdio.h>
#include <ctype.h>
int function(int num);
int main()
{
char input,ch,temp,c[64],exit;
int i,invalid,num,index,flag,day;
invalid = 0;
num = 0;
size_t length = 0;
index = 0;
flag = 0;
do
{
puts("Enter the letter S to start the program:");
scanf("%c", &input);
while( input!='\n' && (ch=getchar())!='\n' && ch!= EOF);
{
if(isalpha(input)==0)
{
printf("Invalid input. Please input something.\n");
continue;
}
if(input == 'S' || input == 's')
{
printf("\nProgram start.");
while( sscanf(c, "%d", &num) != 1)
{
length = 0;
flag = 0;
num = 0;
printf("\nEnter 1 for Module A. Enter 2 for Module B. Enter here: ");
fgets(c, 63, stdin);
length = strlen(c);
for(index = 0; index < length; ++index)
{
if(c[index] < '0' || c[index] > '9')
{
flag = 1;
break;
}
}
if( flag)
{
printf("\nInvalid character\n");
continue;
}
if( sscanf(c, "%d", &num) != 1)
{
printf("\nNo input detected.");
continue;
}
if(num == 1)
{
printf("\nModule A Selected.\n");
return(0);
}
if(num == 2)
{
printf("\nModule B Selected.\n");
return(0);
}
}
}
else
{
printf("\nInvalid input.");
continue;
}
}
}
while(1);
}
Make the scanf into like this.
scanf(" %c",&input);
Then While getting the input from the user using fgets It will place the new line character into that buffer. So this will lead to fails this condition.
if(c[index] < '0' || c[index] > '9')
{
flag = 1;
break;
}
So make the this condition into like this.
length=strlen(c)-1;// to skip the new line character
Or else to like this.
length=strlen(c);
if ( c[length] == '\n' )
c[length]='\0';
Output After placing this,
Enter the letter S to start the program:
S
Program start.
Enter 1 for Module A. Enter 2 for Module B. Enter here: 1
Module A Selected.
Make this in you code.
if(num == 1)
{
printf("\nModule A Selected.\n");
return(0);
}
else if(num == 2)
{
printf("\nModule B Selected.\n");
return(0);
}
else
{
printf("\nInvalid option\n");
c[0]='\0'; // It is for satisfy the second while loop condition.
continue;
}
Note that the loop:
while( input!='\n' && (ch=getchar())!='\n' && ch!= EOF);
is limited to the one line by the semicolon at the end. The following code is not the body of the loop, despite indentation trying to pretend that it is.
Also note that getchar() returns an int, not a char; you cannot reliably assign the result to a char and then test it for EOF. Depending on the platform, you will either never detect EOF at all or you will misdetect EOF when some other character (often ÿ, y-umlaut, U+00FF, LATIN SMALL LETTER Y WITH DIAERESIS) is typed. You must use int ch;.
Here. I fixed the problem using the following code. This way the code does the following:
Scans letters 'S' or 's'. Keeps looping if these are not entered.
Scans either number 1 or 2. Keeps looping until either number is entered and then exits.
The program does not loop from the very beginning (by outputting "Enter 'S' to start program), if any number other than 1 or 2 in entered in part 2 of the program. This was the problem originally.
The following is the correct code:
#include <stdio.h>
#include <ctype.h>
int function();
char input,temp,c[64],ch,exit;
int i,invalid,num,index,flag,start;
start = 0;
invalid = 0;
num = 0;
size_t length = 0;
index = 0;
flag = 0;
int main()
{
do
{
puts("Enter the letter S to start the program: ");
scanf("%c", &input);
while( input!='\n' && (ch=getchar())!='\n' && ch!= EOF);
{
if(isalpha(input)==0)
{
printf("Invalid input. Please input something.\n");
continue;
}
if(input == 'S' || input == 's')
{
printf("\nProgram start.");
start = 1;
if(start == 1)
{
function();
return(0);
}
}
else
{
printf("\nInvalid input.");
continue;
}
}
}
while(1);
}
int function()
{
while( sscanf(c, "%d", &num) != 1)
{
length = 0;
flag = 0;
num = 0;
printf("\nEnter 1 for Module A. Enter 2 for Module B. Enter here: ");
fgets(c, 63, stdin);
length = strlen(c);
length --;
for(index = 0; index < length; ++index)
{
if(c[index] < '0' || c[index] > '9')
{
flag = 1;
break;
}
}
if( flag)
{
printf("\nInvalid character\n");
continue;
}
if( sscanf(c, "%d", &num) != 1)
{
printf("\nNo input detected.");
continue;
}
if(num == 1)
{
printf("\nModule A Selected.\n");
return(0);
}
else if(num == 2)
{
printf("\nModule B Selected.\n");
return(0);
}
else
{
printf("\nInvalid option\n");
c[0]='\0'; // It is for satisfy the second while loop condition.
continue;
}
}
}
Hey everyone thanks for the advise. unfortunately i'm not allowed to use such functions. so i wrote this code, which works great with 1 problem. if i enter lets say 'hhjk' it will freak out. i want to clear the buffer after the first 'h' is detected as non-digit.. heard about the function fflush but i can't get to understand it..
int get_int()
{
char inp; /*inp, for input*/
int number; /*the same input but as integer*/
int flag=0; /*indicates if i need to ask for new input*/
do {
flag=0; /*indicates if i need to ask for new input*/
scanf("%c",&inp);
if (inp<48 || inp>57 ) /*this means it is not a number*/
{
inp=getchar(); /*Here i clear the buffer, the stdin for new input*/
printf("Try again...\n");
flag=1;
}
else
if (inp>53 && inp<58 && flag!=1) /*this means it is a number but not in the 0-5 range*/
{
inp=getchar(); /*here i clear the buffer, the stdin so i can get a new input*/
flag=1;
}
} while (flag);
number=inp-48; /*takes the ascii value of char and make it an integer*/
return number;
}
A simple way is to input a string, then check to make sure everything in there is a character. We can use strtol() to check since it returns a 0 when it can't do the converstion, the only condition is since you want 0 to be valid input, we have to put a special condition on the check:
int main()
{
char input[50]; // We'll input as a character to get anything the user types
long int i = 0;
do{
scanf("%s", input); // Get input as a string
i = strtol(input, NULL, 10); // Convert to int
if (i == 0 && input[0] != '0') { // if it's 0 either it was a numberic 0 or
printf("Non-numeric\n"); // it was not a number
i = -1; // stop from breaking out of while()
}
else if(i<0 || i > 5)
printf("wrong\n");
}while (i < 0 || i >5);
return 0;
}
Another way is to use the seldom seen %[] format for the scanf family. In the code below, I have %[0-9]. This gives us only numbers. ( haven't shown the return code, etc.)
do {
if ((scanf("%[0-9]%c", input, &nl) == 2) && (nl == '\n')) {
value = strtol(input, NULL, 0);
} else {
value = -1;
}
} while ((0 <= value) && (value <= 5));