I have the following program
#include <ncurses.h>
int main() {
initscr();
const char c = static_cast<char>(65);
mvprintw(0, 0, "%s", &c);
getch();
endwin();
return 0;
}
it prints simple "A" and waits.
If I modifying "x" argument of mvprintw
mvprintw(0, 1, "%s", &c);
it will print "A" with empty space prepend on beginning.
If I will add for loop starting from 0 it also works as expected
int main() {
initscr();
for (int i = 0; i < 1; i++) {
const char c = static_cast<char>(65);
mvprintw(0, i, "%s", &c);
}
getch();
endwin();
return 0;
}
will show the same result as in first example.
But if this loop starts from 1 there is stragne ^A at the end.
This code:
int main() {
initscr();
for (int i = 1; i < 2; i++) {
const char c = static_cast<char>(65);
mvprintw(0, i, "%s", &c);
}
getch();
endwin();
return 0;
}
produces
and I even do not know how to debug it?
If mvprintw is anything like printf then you are supposed to provide a nul terminated string when you use %s. Try this instead
const char c[] = { static_cast<char>(65), '\0' };
mvprintw(0, i, "%s", c);
Note in this version c not &c.
Related
I'm doing a quick binary tree program as a homework, but I am getting weird errors that I can't seem to figure out how to fix. Normally I'm programming in C#, and C is just slightly different but different enough for me to get confused.
Here is the code that is giving the error:
void SortArray() {//bubble sorting by float value of 'b'
int flag = 0;
do {
flag = 1;
for (int i = 0; i < arraySize - 1; i++)
{
if (stubList[i].b > stubList[i + 1].b) {
Swap(stubList[i], stubList[i + 1]);
flag = 0;
}
}
} while (flag == 0);
printf("Sorted by value of variable 'b'"); _getch(); _getch();
}
And here is the whole script:
#include <conio.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
using namespace std;
struct stub
{
char crown[51];//some custom name - can be empty
float b;//comparable value for tree sort
int c;//limited by maxint
stub *l;//left node(normally smaller "b" value than this node)
stub *r;//right node(normally bigger "b" value than this node)
};
stub *stubList[255];//empty list of a stub array with a safe casual amount
int arraySize = 0;
stub *head = NULL;//main stub(first)
stub *latest = NULL;//latest stub
stub *st = NULL;//used for creating and checking
FILE *fs = NULL;
char fileName[255];
int maxint = 20;//for var 'c'
void BTreeNodeToArray(stub *s) {
stubList[arraySize] = s;
arraySize++;
}
void Swap(stub &s1, stub &s2) {
stub temp = s2;
s1 = s2;
s2 = temp;
}
int MaxMin(int num) {
int clampedInt = num;
if (num < 0) clampedInt = 0;
else if (num > maxint) clampedInt = maxint;
return clampedInt;
}
//Create a completely new stub with crown, b, and c variables being filled here
void CreateElement() {
st = new stub;
printf("Adding information for node:\n");
printf("Node name: "); gets_s(st->crown);
printf("\n");
float f;
printf("Node float value (B): "); scanf_s("%f", &f);
st->b = f;
printf("\n");
int d;
printf("Node integer value (C): "); scanf_s("%d", &d);
st->c = d;
printf("\n");
st->c = MaxMin(st->c);
st->l = NULL;
st->r = NULL;
}
//creates the very first stub(root/head)
void CreateFirst() {
printf("First in tree. Adding root node...\n");
CreateElement();
head = st;
latest = head;
BTreeNodeToArray(head);
printf("Added head stub\ncrown: %s\nValue: %f\nExtra: %d", head->crown, head->b, head->c);
getchar();
getchar();
}
void AddStub() {
if (head == NULL) {
CreateFirst();
}
else {
CreateElement();//create newest node
latest = st;
st = head;
int depth = 0;
while (1) {
if ((latest->b <= st->b)) {//choose left if true
printf("Went left\n");
depth++;
if (st->l == NULL) {//node free, assign here
printf("Node assigned at depth %d\n", depth);
st->l = latest;
BTreeNodeToArray(latest);
getchar();
getchar();
break;
}
else {//loop again with next node
//printf("New loop (left)\n");
st = st->l;
}
}
else {//choose right
printf("Went right\n");
depth++;
if (st->r == NULL) {//node free, assign here
printf("Node assigned at depth %d\n", depth);
st->r = latest;
BTreeNodeToArray(latest);
getchar();
getchar();
break;
}
else {//loop again with next node
//printf("New loop (right)\n");
st = st->r;
}
}
}
}
}
void ViewArray() {
for (int i = 0; i < arraySize; i++)
{
printf_s("Node [%d]:\n\tCrown: %s\n\tweight: %f\n\tExta value(0 - %d): %d\n", i, stubList[i]->crown, stubList[i]->b, maxint, stubList[i]->c);
}
getchar();
}
void SortArray() {//bubble sorting by float value of 'b'
int flag = 0;
do {
flag = 1;
for (int i = 0; i < arraySize - 1; i++)
{
if (stubList[i].b > stubList[i + 1].b) {
Swap(stubList[i], stubList[i + 1]);
flag = 0;
}
}
} while (flag == 0);
printf("Sorted by value of variable 'b'"); _getch(); _getch();
}
void ProcessArray() {
char c = ' ';
int found = 0;
printf("Process with character: \n"); c = _getch();
if (arraySize <= 0) {
printf("No List!");
return;
}
char chkstr[5];
for (short i = 0; i < 5; i++)//simple assign to a 'string' 5 times
{
chkstr[i] = c;
}
for (int i = 0; i < arraySize; i++)
{
if (strstr(stubList[i]->crown, chkstr) != NULL) {
// contains
printf("B = %f at [%d] \n", stubList[i]->b, i);
found++;
}
}
if (found > 0) {
printf("---Found: %d with character %c---", found, c);
}
else {
printf("No elements found with '%c'", c);
}
getchar();
}
void ExportArray() {
FILE *fs = NULL;
char fileName[255];
errno_t err;
printf("Save to file as: \n"); gets_s(fileName);
if (strlen(fileName) == 0) {
printf("Failed to create file. File name empty!");
_getch();
_getch();
}
err = fopen_s(&fs, fileName, "wb");
if (err != 0) {
printf("Failed to create file!!!");
_getch();
_getch();
return;
}
for (int i = 0; i < arraySize; i++)
{
int written = fwrite(&stubList[i], sizeof(stub), 1, fs);
//fwrite(&gr[i], sizeof(student), 1, fs);
}
int numclosed = _fcloseall();
printf("Exported to file: %s", fileName);
getchar();
}
void CleanReset() {//reset all values and release memory (function used for import)
for (int i = 0; i < arraySize; i++)
{
delete stubList[i];
}
arraySize = 0;
st = NULL;
head = NULL;
latest = NULL;
}
void ImportArray() {
FILE *fs = NULL;
char fname[255];
errno_t err;
printf("Open FIle: "); gets_s(fname);
err = fopen_s(&fs, fname, "rb");
if (err == 0) {
CleanReset();
fseek(fs, 0, SEEK_END);
long size = ftell(fs);
arraySize = size / sizeof(stub);//get amount of students saved
fseek(fs, 0, SEEK_SET);
int i = 0;
st = new stub;
fread_s(&st, sizeof(stub), sizeof(stub), 1, fs);
stubList[i] = st;
while (!feof(fs)) {
i++;
st = new stub;
fread_s(&st, sizeof(stub), sizeof(stub), 1, fs);
stubList[i] = st;
}
printf("File data imported. Size: %d", arraySize);
getchar();
return;
}
printf("Failed to import file!!!");
getchar();
}
void main()
{
system("chcp 65001");//use utf8
char izb = 'i';
while (izb != '0') {
system("cls");
printf_s("1. Add stub\n");
printf_s("2. View Array\n");
printf_s("3. Sort Array\n");
printf_s("4. Process\n");
printf_s("5. Export array to file\n");
printf_s("6. Import array from file\n");
printf_s("0. Exit\n\n");
printf_s("Choose action:\n"); izb = _getch();
switch (izb)
{
case '1':
AddStub();
break;
case '2':
ViewArray();
break;
case '3':
SortArray();
break;
case '4':
ProcessArray();
break;
case '5':
ExportArray();
break;
case '6':
ImportArray();
break;
case '0':
//Exit();
break;
}
}
}
The error is that you want to pass a stub * to a function that wants a stub &. The first one is a pointer, the second one is a reference.
You have two options.
First option (imho recommended):
Change your swap function to accept pointers instead of references.
void Swap(stub *s1, stub *s2) {
stub temp = *s2;
*s1 = *s2;
*s2 = temp;
}
Second option:
Dereference the parameters before passing to swap:
Swap(*(stubList[i]), *(stubList[i + 1]));
You have to undestand that the datatype in your list is a pointer to stub, the function Swap wants a reference, which are different things in C++.
For a better understanding I recommend reading this: https://www.geeksforgeeks.org/pointers-vs-references-cpp/
How to add if-else statement for "kodeprodi"?
Everytime I add if-else statement, the message "Lvalue required" always appears.
#include <iostream>
#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
typedef struct {
char bp[13];
char nama[15];
int kodeprodi;
char namaprodi[10];
float ipk;
} mahasiswa;
int main()
{
char pil;
do {
mahasiswa mhs[10];
int i, n;
{
printf("Data Nilai Mahasiswa\n");
printf("Berapa banyak data = ");
scanf("%d", &n);
for(i = 0; i < n; i++) {
printf("Data mahasiswa ke-%d\n", i+1);
printf("Nomor BP: "); scanf("%s", &mhs[i].bp);
printf("Nama: "); scanf("%s", &mhs[i].nama);
printf("Kode Prodi: "); scanf("%d", &mhs[i].kodeprodi);
printf("IPK: "); scanf("%f", &mhs[i].ipk);
if (mhs[i].kodeprodi == 260) {mhs[i].namaprodi = "SI";}
else if (mhs[i].kodeprodi == 261) {mhs[i].namaprodi = "TI";}
}
//output
printf("No. BP Nama Kode Prodi Nama Prodi IPK \n");
for(i = 0; i < n; i++) {
printf("\n%2d %-10s %-9s %3d %3s %3.f\n",
i+1, mhs[i].bp, mhs[i].nama, mhs[i].nama,
mhs[i].kodeprodi, mhs[i].namaprodi, mhs[i].ipk);
}
}
printf("Repeat again? Y/N");
scanf("%s", &pil);
printf("\n\n");
} while ((pil == 'Y') || (pil == 'y'));
}
Even if in the statement if-else, I type like this
if(mhs[i].kodeprodi==260){namaprodi = "SI");
The error message is "Undefined symbol 'namaprodi'
I tweaked your code a bit. Got rid of unused conio.h, changed kodeprodi type to int (because char can only handle numbers -127..127), removed & from some scanf calls (because you should pass pointer to first character for %s formatter), deleted extra mhs[i].nama argument for printf.
Sorry, I completely didn't understood your code :-) My tweaks were semi-automatic! You should learn C programming better.
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
typedef struct {
char bp[13];
char nama[15];
int kodeprodi;
char namaprodi[10];
float ipk;
} mahasiswa;
int main() {
char pil;
do {
mahasiswa mhs[10];
int i, n;
{
printf("Data Nilai Mahasiswa\n");
printf("Berapa banyak data = ");
scanf("%d", &n);
for(i=0;i<n;i++) {
printf("Data mahasiswa ke-%d\n", i+1);
printf("Nomor BP: "); scanf("%s", mhs[i].bp);
printf("Nama: "); scanf("%s", mhs[i].nama);
printf("Kode Prodi: "); scanf("%d", &mhs[i].kodeprodi);
printf("IPK: "); scanf("%f", &mhs[i].ipk);
if(mhs[i].kodeprodi==260)
strcpy(mhs[i].namaprodi, "SI");
else if(mhs[i].kodeprodi==261)
strcpy(mhs[i].namaprodi, "TI");
}
//output
printf("No. BP Nama Kode Prodi Nama Prodi IPK \n");
for(i=0;i<n;i++) {
printf("\n%2d %-10s %-9s %3d %3s %3.f\n", i+1, mhs[i].bp, mhs[i].nama, mhs[i].kodeprodi, mhs[i].namaprodi, mhs[i].ipk);
}
}
printf("Repeat again? Y/N");
scanf("%s", &pil);
printf("\n\n");
} while ((pil == 'Y') || (pil == 'y'));
return 0;
}
For a quick fix, use:
if(mhs[i].kodeprodi==260){strncpy(mhs[i].namaprodi, "SI", 9);
strncpy() is needed to copy the contents into namaprodi.
namaprodi is a member of struct mahasiswa, so you can't access it directly.
But better use std::string instead.
Also, as #BoPersson mentioned, char kodeprodi; can't hold 260, so you'll better to convert that to an int.
Here is what I get when I try to encrypt "This is a test sentence!": "Ymnxp���p�����t�������"
I have tested my encryption part before and it worked fine.
Can anyone please tell me what did I do wrong here?
#include <iostream>
#include <string>
#include <fstream>
#include <stdlib.h>
#include <stdio.h>
#include "unistd.h"
using namespace std;
void displayUsage(){
// Displays how to use this program
// TODO
cout << "Instruction: \n use -r to give rotation number \n use -f to give file name" <<endl;
}
int main(int argc, char **argv){
string text;
char* input_file_name;
int rotation;
bool have_rotation = false;
bool have_input_file_name = false;
// process command-line arguement
int opt = 0;
extern char *optarg;
static const char* opt_string = "r:f:";
opt = getopt( argc, argv, opt_string);
while(opt != -1) // While there are parameters to parse, do so
{
switch(opt)
{
case 'r':
have_rotation = true;
rotation = atoi(optarg);
break;
case 'f':
have_input_file_name = true;
input_file_name = optarg;
break;
default:
displayUsage();
return 1;
}
opt = getopt( argc, argv, opt_string); // Pull the next parameter, or 0 if none.
}
if(!have_rotation)
{
displayUsage();
return 0;
}
if(have_rotation)
{
if(have_input_file_name)
{
ifstream file(input_file_name);
string text2, temp;
while(!file.eof())
{
getline(file, temp);
text2 += temp;
text2 += "\n";
}
text = text2[text2.size()-2];
}
else
{
cout <<"Enter text:"<<endl;
cin >> text;
}
}
char cipher[text.size()];
for(int i=0; i<text.size(); i++)
{
cipher[i] = text[i];
if(islower(cipher[i]))
{
cipher[i] = (cipher[i] - 'a' + rotation)%26 + 'a';
}
else if(isupper(cipher[i]))
{
cipher[i] = (cipher[i] - 'A' + rotation)%26 + 'A';
}
}
cout <<cipher<<endl;
return 0;
}
I guess the error is because you did not terminate your cipher array with a '\0'.
The printing function will process characters from an array (and possibly beyond) until it finds a '\0' character.
Your array should be one bigger to account for this terminating character.
Or get rid of the char array and use std::string.
I can get my code run if I type the sentence manually. It doesn't printout anything if I input a text file.
#include <iostream>
#include <string>
#include <fstream>
#include <stdlib.h>
#include <stdio.h>
#include "unistd.h"
using namespace std;
void displayUsage(){
// Displays how to use this program
// TODO
cout << "Instruction: \n use -r to give rotation number \n use -f to give file name" <<endl;
}
char caesar(char c, int r)
{
if(isalpha(c))
{
if(islower(c))
{
c = (((c-97)+r)%26)+97; // 97 is a value of 'a'
}
else if(isupper(c))
{
c = (((c-65)+r)%26)+65; // 65 is a value of 'A'
}
}
return c;
}
int main(int argc, char **argv){
string text;
char* input_file_name;
int rotation;
bool have_rotation = false;
bool have_input_file_name = false;
// process command-line arguement
int opt = 0;
extern char *optarg;
static const char* opt_string = "r:f:";
opt = getopt( argc, argv, opt_string);
while(opt != -1) // While there are parameters to parse, do so
{
switch(opt)
{
case 'r':
have_rotation = true;
rotation = atoi(optarg);
break;
case 'f':
have_input_file_name = true;
input_file_name = optarg;
break;
default:
displayUsage();
return 1;
}
opt = getopt( argc, argv, opt_string); // Pull the next parameter, or 0 if none.
}
if(!have_rotation)
{
displayUsage();
return 0;
}
if(have_rotation)
{
if(have_input_file_name)
{
ifstream file(input_file_name);
string text2, temp;
while(!file.eof())
{
getline(file, temp);
text2 += temp + "\n";
}
text = text2[text2.size()-2];
}
else
{
cout <<"Enter text:"<<endl;
getline(cin, text);
}
}
string output = "";
for(int i = 0; i < text.size(); i++)
{
output += caesar(text[i],rotation);
}
cout<<output<<endl;
return 0;
}
I work with C++ and SQLite3 (with Microsoft Visual C++ 2008) and would like to read a value from my database and store it in a variable to work with it on.
The select statement works fine, but every time I viewed the callback function and try to read the value from char **argv, I get "only" the memory address, or the first ASCII character of the value, which is in the database. What am I doing wrong?
Here is the callback function:
static int callback(void *pArg, int argc, char **argv, char **azColName)
{
fprintf(f, "Callback aufgerufen!\n");
int i;
for(i=0; i<argc; i++)
{
fprintf(f, azColName[i]);
fprintf(f, " = ");
if(argv[i]){
fprintf(f, argv[i]);
//unsigned int x = argv[i];
}
else
fprintf(f, "NULL");
fprintf(f, "\n");
}
fprintf(f, "\n");
return 0;
}
I tried it without the callback function, but again I get the same result and I've tried different ways to store the value in a variable.
while (sqlite3_step(stmt) == SQLITE_ROW)
{
fprintf(f, "%s\n", sqlite3_column_text(stmt, 0));
//const unsigned char *c = sqlite3_column_text(stmt, 0);
fprintf(f, "%u\n", sqlite3_column_int(stmt, 0));
//unsigned int z = *sqlite3_column_int(stmt, 0);
stmt_count++;
}
Is it perhaps not possible to access the value or to store it in a variable?
I don't see why you need a callback - this should work (depending on the size of the data):
char myvalue[100];
while (sqlite3_step(stmt) == SQLITE_ROW)
{
strcpy( myvalue, (const char *) sqlite3_column_text(stmt, 0) );
// do something with myvalue
stmt_count++;
}
I want to print an array of characters, these characters are underscores first.
Then the user can write characters on these underscores.I used gotoxy() but it doesn't work properly.
That is what i wrote:
int main(void)
{
char arr[20];
int i;
char ch;
clrscr();
for(i=0;i<=20;i++)
{
textattr(0x07);
cprintf("_");
}
do
{
for(i=0;i<=20;i++)
{
//gotoxy(i,0);
//ch = getche();
if( isprint(ch) == 1)
{
arr[i] = ch;
gotoxy(i,0);
//printf("%c",ch);
}
}
} while(i == 20);
getch();
return 0;
}
The first thing is this: You probably don't want to have all those calls to gotoxy, textattr and cprintf in your main function, since that is not what the main function is supposed to do.
It is much more likely that the main function's purpose is "to read some text from the user, presented nicely in an input field". So you should make this a function:
static int
nice_input_field(char *buf, size_t bufsize, int x, int y) {
int i, ch;
gotoxy(x, y);
for (i = 0; i < bufsize - 1; i++) {
cprintf("_");
}
i = 0;
gotoxy(x, y);
while ((ch = readkey()) != EOF) {
switch (ch) {
case '...': /* ... */
break;
case '\b': /* backspace */
cprintf("_");
i--;
gotoxy(x + i, y);
break;
case '\t': /* tabulator */
case '\n': /* enter, return */
buf[i] = '\0';
return 0; /* ok */
default: /* some hopefully printable character */
if (i == bufsize - 1) {
cprintf("\a"); /* beep */
} else {
buf[i++] = ch;
gotoxy(x + i, y);
cprintf("%c", buf[i]);
}
}
}
/* TODO: null-terminate the buffer */
return 0;
}
Printing an array of characters is fairly easy:
char* str = your_array;
while(*str) {
putc(*str++);
}
From memory that should print a string out to the screen.
Your code is very DOS-specific. There is not a good general solution to the problem of reading immediate input in a portable way. It does get asked quite often, so I think the C FAQ broke down and included an answer which you might want to seek out.
That said, I think your bug is that gotoxy(1, 1) is the upper corner of the screen, not 0,0. So you want gotoxy(i, 1)