I want to enter the text and specific character.
After that i want to count how many those characters contain in the text.
My code
#include <stdio.h>
#include <stdlib.h>
int counting(char text[], char character);
int main()
{
char text[20];
char character;
int a;
printf("Enter text!\n");
scanf("%s", text);
printf("Enter character!\n");
scanf("%s", character);
a= counting(text, character);
printf("Text contain %d character!\n", a);
}
And the counting function
int counting(char text[], char character)
{
int i=0;
int counter=0;
while(text[i] != '\0')
{
if (text[i]==character)
{
counter++;
}
}
i++;
return counter;
}
Error:
The line for reading the character needs to be:
scanf(" %c", &character);
Also,
scanf("%s", text);
is not safe. If the user enter a string that is longer than 19 characters, you will be writing over unauthorized memory, which will lead to undefined behavior.
Use
scanf("%19s", text);
In function int counting(...)
while(text[i] != '\0')
{
if (text[i]==character)
{
counter++;
}
}
i++;
Need i++ inside your while..loop.
You have two problems.
1)You are reading the specific character as a string so you have to change scanf("%s", character); to scanf(" %c", character);
2)In function counting() i++ needs to be in while loop so you don't enter an infinite loop.
Related
I'm supposed to be writing code that takes a string of comma separated values without spaces (ex. my,name,is,jack). First we had to write a function
string nextstring(string str, int start_index)
that returns a single "value" from your initial string depending on the start index. The second part of the problem was to write a function
int split(string str, string a[], int max_size)
that will identify all the values in the initial string and put them in a string array and then return the total number of values stored in the array; i.e. if you had initially input my,name,is it would return 3.
My function never returns the correct value and whatever it returns changes depending on what the length of the words are.
#include <iostream>
#include <string>
using namespace std;
string nextstring(string str, int start_index);
int split(string str, string a[], int max_size);
int main()
{
string str;
int cnt;
string a[100];
cout<< "what is your string" << endl;
getline(cin, str);
cnt= split(str, a, 100);
cout << "There are " << cnt << " values in this string" << endl;
for(int i=0; i<cnt; i++)
{
cout << a[i] << endl;
}
return 0;
}
string nextstring(string str, int start_index)
{
string ans;
if(str[start_index] == ',' || str[start_index] == '\0')
{
ans=" ";
}
else{
ans=str[start_index]+nextstring(str, start_index+1);
}
return ans;
}
int split(string str, string a[], int max_size)
{
int j=0;
int ans=0;
double k=0;
while(j<max_size)
{
a[j]= nextstring(str,k);
string check=a[j];
if(isalpha(check[0])!= 0)
{
ans++;
}
k=k+a[j].length();
j++;
}
return ans;
}
It seems that your problem is that while(j<max_size){...} leads to j being incremented up to max_size. The line a[j]= nextstring(str,k); is at some points reading values that are outside your string which is really bad!
Replacing while(j<max_size){...} by while(j<max_size && k<str.length()){...} seems to be enough to make your code work!
Apart from that:
k has no reason to be a double! It should be an int (or something similar).
Since you are already using string, you should also learn to use vector. split is better written as:
int split(string str, vector<string> &a, int max_size)
{
int ans=0;
int k=0;
while(k<str.length())
{
string next = nextstring(str,k);
if(isalpha(next[0])!= 0)
{
ans++;
a.append(next);
}
k += next.length();
}
return ans;
}
The problem in your approach is to identify the end of the string, as there is no null terminator in a c++ string. Consider to update nextstring() to look for the end of string in a different manner:
string nextstring(string str, int start_index)
{
...
if(start_index == str.size() || str[start_index] == ',' ) //<===
{
ans=" ";
}
...
}
online demo
Additional recommendation
Note that it is not very nice to return a blank string when in reality it should be empty to reflect its real value (e.g. ",,"). You have no choice because otherwise you would have no mean in the calling function, to determine that the end of string was reached. But the consequence is thar all your strings have a trailing blank.
When you call recursively the function adding char to build the return string, you risk to have a considerable overhead. You could consider avoiding this, by replacing the else part:
ans=str.substr(start_index, str.find(',', start_index+1)-start_index);
However, as you have no trailing blank anymore, you need to adapt split() so to adapt its way to count the total number of chars parsed:
k=k+a[j].length()+1; // +1 because there's no longer a trailing blank.
Online demo
I am currently doing a practice problem in hacker rank. The link is : https://www.hackerrank.com/challenges/linkedin-practice-dictionaries-and-maps
#include<cstdio>
#include<map>
#include<vector>
#include<conio.h>
#include<iostream>
#include<string>
using namespace std;
map<std::string, int> dict;
map<std::string, int>::iterator k;
int i, j, temp, n;
long long num;
//char check[100][100];
std::string str, sea;
int main()
{
scanf("%d", &n);
j = n;
while(j--)
{
scanf("%s %d", &str, &num);
dict.insert(make_pair(str, num));
}
printf("finished\n");
printf("%s %d\n", "sam", dict["sam"]);
while(scanf("%s", str))
{
if(str.empty())
break;
//printf("k is %s\n",str);
k = dict.find(str);
if(k != dict.end())
{
printf("%s %d\n", str, dict[str]);
}
else
{
printf("Not found\n");
}
}
getch();
}
The program runs fine until the printf statement "finished". Then in the next output for the dict statement occurs as
finished
sam 0
And in while statement, when it searches for string in map, the application hangs, and closes automatically. While inserting values I tried to use:
dict[str] = num;
dict.insert(pair(str, num));
dict.insert(make_pair(str, num));
Please mention if there is any corrections I need to do in the program. Any help is appreciated. Thanks!
This statement,
scanf("%s %d", &str, &num);
… is not a valid way to input a std::string. It has Undefined Behavior. All bets are off.
You can input to a char buffer, and conveniently std::string provides such a buffer. E.g.
str.resize( max_item_length );
scanf("%s %d", &str[0], &num);
str.resize( strlen( &str[0] ) );
Of course you can just use C++ iostreams instead, throughout the code, e.g.
cin >> str >> num;
I'm very new at C++, maintaining my M.Sc on Information Systems. I have my first C++ homework announced and have been working on it for a couple of days. The aim of the code is simply to read info from a text file and print it on screen, then make calculation on some of it and print results to a new text file. However when I build, it gives the error:
EXC_BAD_ACCESS (code=EXC_I386_GBFLT)
in the first fscanf in readInfo function.
I know the code I wrote is not completely efficient but I just want it to print on screen and on output file correctly. I would really appreciate if anyone help me to resolve this error. I am about to freak out...
#include <stdio.h>
typedef struct {
char id[10];
char name[40];
float midterm;
float final;
int attendance;
}Student;
void readInfo(Student studentList[], int *count)
{
FILE *fin=fopen("scores.txt","r");
char surname = '\0';
*count=0;
while(!feof(fin))
{
fscanf(fin,"%c %c %c %f %f %d",studentList[*count].id, studentList[*count].name, &surname, &studentList[*count].midterm, &studentList[*count].final, &studentList[*count].attendance);
strcpy(studentList[*count].name, studentList[*count].name);
strcat(studentList[*count].name, " ");
strcat(studentList[*count].name, &surname);
*count++;
}fclose(fin);
printf("%-7s%17s %5.1f %5.1f %-2d\n", studentList[*count].id, studentList[*count].name, studentList[*count].midterm, studentList[*count].final, studentList[*count].attendance);
}
float studentScore(float midterm, float final, int attendance)
{
float score;
int maxAttend=0;
char id[10];
char name[40];
char surname[40];
FILE *fin=fopen("scores.txt","r");
while(!feof(fin))
{
fscanf(fin,"%c %c %c %f %f %d",id, name, surname, &midterm, &final, &attendance);
if(attendance>maxAttend)
maxAttend=attendance;
}fclose(fin);
score=midterm*0.3+final*0.5+(maxAttend/20)*attendance;
return score;
}
float avgScore(Student studentList[])
{
float average;
int count;
int totalScore=0;
readInfo(studentList, &count);
for(int i=0; i<=count; i++)
{
totalScore+=studentScore(studentList[count].midterm, studentList[count].final, studentList[count].attendance);
}
average=totalScore/count;
return average;
}
void courseGradeOutput(Student studentList[])
{
FILE *fout=fopen("output.txt","w");
int count;
int pass=0;
float score;
char letterGrade[2];
float avg;
fprintf(fout,"\tId\tName, Surname = (Score, Letter)\n");
readInfo(studentList, &count);
for(int i=0; i<=count; i++)
{
score=studentScore(studentList[i].midterm, studentList[i].final, studentList[i].attendance);
if(score>=0 && score<=49)
{ letterGrade[0]={'F'};
letterGrade[1]={'F'};}
else if (score>=50 && score<=59)
{letterGrade[0]={'F'};
letterGrade[1]={'D'};}
else if (score>=60 && score<=64)
{letterGrade[0]={'D'};
letterGrade[1]={'D'};}
else if (score>=65 && score<=69)
{letterGrade[0]={'D'};
letterGrade[1]={'C'};}
else if (score>=70 && score<=74)
{letterGrade[0]={'C'};
letterGrade[1]={'C'};}
else if (score>=75 && score<=79)
{letterGrade[0]={'C'};
letterGrade[1]={'B'};}
else if (score>=80 && score<=84)
{letterGrade[0]={'B'};
letterGrade[1]={'B'};}
else if (score>=85 && score<=89)
{letterGrade[0]={'B'};
letterGrade[1]={'A'};}
else if (score>=90 && score<=100)
{letterGrade[0]={'A'};
letterGrade[1]={'A'};}
if(score>=60)
pass++;
fprintf(fout,"%7s %16s = ( %4.1f, %6s\n)", studentList[i].id, studentList[i].name, score, letterGrade);
}
avg=avgScore(studentList);
fprintf(fout,"\nSome statistics:\n\nClass Avg Score: %5.2f \n #Students: %11d \n #Passed Students: %4d \n #Failed Students: %4d",avg,count,pass,(count-pass));
fclose(fout);
}
int main()
{ Student studentList[100];
int count;
readInfo(studentList, &count);
courseGradeOutput(studentList);
}
Screenshot
The crash is most likely caused by either fscanf followed by strcpy and/or by your increment of count inside readInfo.
You write *count++, but this is equivalent to
count = count + 1;
*(count-1);
What you want is (*count)++.
The fscanf scans characters %c where you want to scan strings %s (for id and name). You also want to scan surname as a string, probably, but then you need to change surname to be a character array:
char surname[30];
*count=0;
while(!feof(fin))
{
fscanf(fin,"%s %s %s %f %f %d",studentList[*count].id, studentList[*count].name, surname, &studentList[*count].midterm, &studentList[*count].final, &studentList[*count].attendance);
strcat(studentList[*count].name, " ");
strcat(studentList[*count].name, surname);
(*count)++;
}
fclose(fin);
I also removed the first strcpy as you were copying from a buffer to itself, which is not allowed.
I haven't checked the other functions thoroughly, but I do notice that you do not use the result from your readInfo called from main when you do courseGradeOutput: this function calls readInfo again. You could modify it to take the read student records and the count, so you don't have to read the file again.
You might also want to improve scanf a bit to pass a width, such as %29s for name, to avoid overflowing the buffer when the name inside the file is too long; and the same for the other strings you scan. You should then also look at the return value of fscanf and only use the things you scanned when it succeeded in scanning every argument.
I wrote a simple C++ program to reverse a string. I store a string in character array. To reverse a string I am using same character array and temp variable to swap the characters of an array.
#include<iostream>
#include<string>
using namespace std;
void reverseChar(char* str);
char str[50],rstr[50];
int i,n;
int main()
{
cout<<"Please Enter the String: ";
cin.getline(str,50);
reverseChar(str);
cout<<str;
return 0;
}
void reverseChar(char* str)
{
for(i=0;i<sizeof(str)/2;i++)
{
char temp=str[i];
str[i]=str[sizeof(str)-i-1];
str[sizeof(str)-i-1]=temp;
}
}
Now this method is not working and, I am getting the NULL String as result after the program execution.
So I want to know why I can't equate character array, why wouldn't this program work. And what is the solution or trick that I can use to make the same program work?
sizeof(str) does not do what you expect.
Given a char *str, sizeof(str) will not give you the length of that string. Instead, it will give you the number of bytes that a pointer occupies. You are probably looking for strlen() instead.
If we fixed that, we would have:
for(i=0;i<strlen(str)/2;i++)
{
char temp=str[i];
str[i]=str[strlen(str)-i-1];
str[strlen(str)-i-1]=temp;
}
This is C++, use std::swap()
In C++, if you want to swap the contents of two variables, use std::swap instead of the temporary variable.
So instead of:
char temp=str[i];
str[i]=str[strlen(str)-i-1];
str[strlen(str)-i-1]=temp;
You would just write:
swap(str[i], str[sizeof(str) - i - 1]);
Note how much clearer that is.
You're using C++, just use std::reverse()
std::reverse(str, str + strlen(str));
Global variables
It's extremely poor practice to make variables global if they don't need to be. In particular, I'm referring to i about this.
Executive Summary
If I was to write this function, it would look like one of the two following implementations:
void reverseChar(char* str) {
const size_t len = strlen(str);
for(size_t i=0; i<len/2; i++)
swap(str[i], str[len-i-1]);
}
void reverseChar(char* str) {
std::reverse(str, str + strlen(str));
}
When tested, both of these produce dlrow olleh on an input of hello world.
The problem is that within your function, str is not an array but a pointer. So sizeof will get you the size of the pointer, not the length of the array it points to. Also, even if it gave you the size of the array, that is not the length of the string. For this, better use strlen.
To avoid multiple calls to strlen, give the function another parameter, which tells the length:
void reverseChar(char* str, int len)
{
for(i=0; i<len/2; i++)
{
char temp=str[i];
str[i]=str[len-i-1];
str[len-i-1]=temp;
}
}
and call it with
reverseChar(str, strlen(str))
Another improvement, as mentioned in the comments, is to use std::swap in the loop body:
void reverseChar(char* str, int len)
{
for(i=0; i<len/2; i++)
{
std::swap(str[i], str[len-i-1]);
}
}
Also, there is std::reverse which does almost exactly that.
//reverse a string
#include<iostream>
using namespace std;
int strlen(char * str) {
int len = 0;
while (*str != '\0') {
len++;
str++;
}
return len;
}
void reverse(char* str, int len) {
for(int i=0; i<len/2; i++) {
char temp=str[i];
str[i]=str[len-i-1];
str[len-i-1]=temp;
}
}
int main() {
char str[100];
cin.getline(str,100);
reverse(str, strlen(str));
cout<<str<<endl;
getchar();
return 0;
}
If I were you, I would just write it like so:
int main()
{
string str;
cout << "Enter a string: " << endl;
getline(cin, str);
for (int x = str.length() - 1; x > -1; x--)
{
cout << str[x];
}
return 0;
}
This is a very simple way to do it and works great.
#include <iostream>
#include <cstdio>
using namespace std;
int main()
{
char str[80];
cout << "Enter a string bro: \n";
gets_s(str);
for (int i = strlen(str) - 1; i > -1; i--)
{
cout << str[i];
}
}
how do I pass a char vector to a char*? I know this problem could easily be solved with a predefined char[] array with a SIZE const, but I want the flexibility of a vector because there will be no predefined size.
using namespace std;
//prototype
void getnumberofwords(char*);
int main() {
//declare the input vector
vector<char> input;
/*here I collect the input from user into the vector, but I am omitting the code here for sake of brevity...*/
getnumberofwords(input);
//here is where an ERROR shows up: there is no suitable conversion from std::vector to char*
return 0;
}
void getnumberofwords(char *str){
int numwords=0;
int lengthofstring = (int)str.size();
//this ERROR says the expression must have a case
//step through characters until null
for (int index=0; index < lengthofstring; index++){
if ( *(str+index) == '\0') {
numwords++;
}
}
}
You can use data() member to get the pointer to the underlying array:
getnumberofwords(input.data());
The most obvious is to pass &your_vector[0]. Be sure to add a NUL to the end of your vector first though.
Alternatively, use std::string instead of std::vector<char>, in which case you can get a NUL-terminated string with the c_str member function.
Edit: I have to wonder, however, why getnmberofwords would be written to accept a char * unless it's some old C code that you just can't get away from using.
Given a typical definition of "word" counting some words that start out in a string can be done something like this:
std::istringstream buffer(your_string);
size_t num_words = std::distance(std::istream_iterator<std::string>(buffer),
std::istream_iterator<std::string>());
You should pass the reference of the vector to the function getnumberofwords.
void getnumberofwords(vector<char>& str){
int numwords=0;
int lengthofstring = str.size();
for (int index=0; index < lengthofstring; index++){
if ( str[index] == '\0') {
numwords++;
}
}
}
There is no method for converting the type from vector to pointer.
here's what I ended up doing which worked:
#include <iostream>
#include <cstring>
#include <string>
#include <iomanip>
using namespace std;
//prototype
void getnumberofwords(char*);
void getavgnumofletters(char*, int);
int main() {
const int SIZE=50;
char str[SIZE];
cout<<"Enter a string:";
cin.getline(str, SIZE);
getnumberofwords(str);
return 0;
}
void getnumberofwords(char *str){
int numwords=0;
int lengthstring=strlen(str);
//step through characters until null
for (int index=0; index < lengthstring; index++){
if (str[index] ==' ') {
numwords++;
}else{
continue;
}
}
numwords+=1;
cout<<"There are "<<numwords<<" in that sentence "<<endl;
getavgnumofletters(str, numwords);
}
void getavgnumofletters(char *str, int numwords) {
int numofletters=0;
double avgnumofletters;
int lengthstring=strlen(str);
//step through characters until null
for (int index=0; index < lengthstring; index++){
if (str[index] != ' ') {
numofletters++;
}else{
continue;
}
}
avgnumofletters = (double)numofletters/numwords;
cout<<"The average number of letters per word is "<<setprecision(1)<<fixed<<avgnumofletters<<endl;
}
/*