I want to use this code (from my last question (thanks Adam)),
bool AllDigitsIdentical(int number)
{
int lastDigit = number % 10;
number /= 10;
while(number > 0)
{
int digit = number % 10;
if(digit != lastDigit)
return false;
number /= 10;
}
return true;
}
but the compiler just says in the second line at } :
Nested functions are disabled, use -fnested-functions to re-enable
What can I do in my case? I have no plan…
Thanks and sorry for my bad English.
You wouldn't happen to have something like:
- (void) someMethod
{
bool AllDigitsIdentical(int number)
{
int lastDigit = number % 10;
number /= 10;
while(number > 0)
{
int digit = number % 10;
if(digit != lastDigit)
return false;
number /= 10;
}
return true;
}
}
That is, you have a function declared within a method's scope of implementation (though the same problem would occur for a function declared within a function).
In short, don't do that. It isn't supported and the means via which GCC implements it is considered to be a bit of a security hole (IIRC).
Move it outside:
bool AllDigitsIdentical(int number)
{
int lastDigit = number % 10;
number /= 10;
while(number > 0)
{
int digit = number % 10;
if(digit != lastDigit)
return false;
number /= 10;
}
return true;
}
- (void) someMethod
{
.... call the function here ....
}
this function looks fine, is it possible you missed a closing } in the code before this function ?
You probably pasted that into a method or into your main function! Make sure that that chuck of code is put OUTSIDE any other blocks of code.
so if you have main here:
int main(int argc, char **argv){
//blah
}
make sure that you put that code above or below it like so:
bool AllDigitsIdentical(int number){
//blah
}
do NOT put it inbetween the { or } of the main function (or any other method)
Related
enter image description here
Sorry im new to coding . I have searched up possible solutions for this on here but they didnt work. Im also confused on why some code appears grey compared to the rest.
https://1drv.ms/w/s!Ag8vVFKVPyOg6HeYLehGjQKdvl_3?e=QHY6t9
#include <stdio.h>
// initialised variables
int i = 0;
int count = 0;
void displayfunction(void);
int month = 0;
void highervalues(float array1[12], float array2[12]);
void highervalues(float array1[12], float array2[12]) {
for (i = 12; i > 0; i--) {
if (array2[i] > array1[i]) {
count = count + 1;
}
}
}
//Reading values for array1 and array2
void displayfunction(void) {
highervalues(array1[12] , array2[12]);
for (i = 0; i < 12; i++)
{
month = month + 1; // month increases by 1 after each input
printf_s("enter values for year 1 month %d", month);
scanf_s("%f", &array1[i]);
}
for (month = 12; month > 0; month--) {
}
for (i = 0; i < 12; i++) {
month = month + 1;
printf_s("enter values for year 2 month %d", month);
scanf_s("%f", &array2[i]);
}
}
/*comapring 2 arrays and increasing count value if there are any value in array2
are greater than array1*/
int main() {
displayfunction();
int array1[12];
int array2[12];
}
You have a fundamental misunderstanding of variable scope
int main() {
displayfunction();
int array1[12];
int array2[12];
}
Those arrays are only available in main. If you want other functions to operate on them you have to pass them as paramters to those functions. Plus they dont exist at the point where you try to call displayFunction
So change
void displayfunction(void)
to
void displayfunction(float array1[12], float array2[12])
then in main do
int main() {
int a1[12];
int a2[12];
displayfunction(a1, a2);
}
Note that I have changed the names here just to emphasise that its the not the fact that the names are the same thats important.
I'm trying to use qsort to sort a C array in descending order based on what this website is suggesting.
Here is the relevant code:
int x = 3;
- (IBAction)CaptureButton:(id)sender
{
x++;
if (x % 3 == 1)
{
int areas[detectedBlobs.size()];
for (int i = 0; i < detectedBlobs.size(); i++)
{
areas[i] = detectedBlobs[i].getWidth() * detectedBlobs[i].getHeight();
}
int compareInts(void const *item1, void const *item2)
{ // first error
int const *int1 = item1;
int const *int2 = item2;
return (*int2 - *int1);
}
qsort(areas, detectedBlobs.size(), sizeof(int), compareInts); // second error
}
}
Here are the two errors I'm getting:
First error:
Function definition is not allowed here
Second error:
Use of undeclared identifier 'compareInts'
If I cannot define the comparator (compareInts) function here, where do I have to define it? Also, how can I get the qsort function to recognize the comparator?
Objective-C does not allow function definitions inside methods. Move compareInts outside of the method, and make it static to hide from other translation units:
static int compareInts(const void* item1, const void* item2) {
const int* int1 = (const int*)item1;
const int* int2 = (const int*)item2;
return (*int2 - *int1);
}
- (IBAction)CaptureButton:(id)sender {
x++;
if (x % 3 == 1) {
int areas[detectedBlobs.size()];
for (int i = 0; i < detectedBlobs.size(); i++) {
areas[i] = detectedBlobs[i].getWidth() * detectedBlobs[i].getHeight();
}
qsort(areas, detectedBlobs.size(), sizeof(int), compareInts);
}
}
I am translating an Obj-C app to Swift and having trouble dealing with some syntax. I believe I have declared the variable types correctly so I don't know why I'm be getting these errors. Maybe some blocks are located incorrectly inside classes/functions when they should be outside or something. I would love it if you could review my code. I'm new to programming so what may be a clear and explicit explanation to you probably will still be vague for me so please show with examples using existing names.
Thanks
"Unary operator '++' cannot be applied to an operand of type 'Int?'"
and
"Binary operator '<' cannot be applied to an operand of type 'Int? and Float'"
and
"Use of unresolved identifier '=-'"
import UIKit
import Foundation
import AVFoundation
let minFramesForFilterToSettle = 10
enum CurrentState {
case statePaused
case stateSampling
}
class ViewController: UIViewController, AVCaptureVideoDataOutputSampleBufferDelegate {
let session = AVCaptureSession()
var camera : AVCaptureDevice?
var validFrameCounter: Int = 0
var pulseDetector: PulseDetector!
var filter: Filter!
var currentState = CurrentState.stateSampling // Is this initialized correctly?
override func viewDidLoad() {
super.viewDidLoad()
self.pulseDetector = PulseDetector()
self.filter = Filter()
// TO DO startCameraCapture() // call to un-used function.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
let NZEROS = 10
let NPOLES = 10
class Filter {
var xv = [Float](count: NZEROS + 1, repeatedValue: 0)
var yv = [Float](count: NPOLES + 1, repeatedValue: 0)
func processValue(value: Float) -> Float {
let gain: Float = 1.894427025e+01
xv[0] = xv[1]; xv[1] = xv[2]; xv[2] = xv[3]; xv[3] = xv[4]; xv[4] = xv[5]; xv[5] = xv[6]; xv[6] = xv[7]; xv[7] = xv[8]; xv[8] = xv[9]; xv[9] = xv[10]; xv[10] = value / gain;
yv[0] = yv[1]; yv[1] = yv[2]; yv[2] = yv[3]; yv[3] = yv[4]; yv[4] = yv[5]; yv[5] = yv[6]; yv[6] = yv[7]; yv[7] = yv[8]; yv[8] = yv[9]; yv[9] = yv[10];
yv[10] = (xv[10] - xv[0]) + 5 * (xv[2] - xv[8]) + 10 * (xv[6] - xv[4])
+ ( -0.0000000000 * yv[0]) + ( 0.0357796363 * yv[1])
+ ( -0.1476158522 * yv[2]) + ( 0.3992561394 * yv[3])
+ ( -1.1743136181 * yv[4]) + ( 2.4692165842 * yv[5])
+ ( -3.3820859632 * yv[6]) + ( 3.9628972812 * yv[7])
+ ( -4.3832594900 * yv[8]) + ( 3.2101976096 * yv[9]);
return yv[10];
}
}
let maxPeriod = 1.5 // float?
let minPeriod = 0.1 // float?
let invalidEntry:Double = -11
let maxPeriodsToStore:Int = 20
let averageSize:Float = 20
class PulseDetector {
var upVals: [Float] = [averageSize]
var downVals: [Float] = [averageSize]
var upValIndex: Int?
var downValIndex: Int?
var lastVal: Float?
var periodStart: Float?
var periods: [Double] = []
var periodTimes: [Double] = []
var periodIndex: Int?
var started: Bool?
var freq: Float?
var average: Float?
var wasDown: Bool?
func reset() {
for var i=0; i < maxPeriodsToStore; i++ {
periods[i] = invalidEntry
}
for var i=0; i < averageSize; i++ { // why error when PulseDetector.h said averageSize was an Int?
upVals[i] = invalidEntry
downVals[i] = invalidEntry
}
freq = 0.5
periodIndex = 0
downValIndex = 0
upValIndex = 0
}
func addNewValue(newVal:Float, atTime:Double) -> Float {
// we keep track of the number of values above and below zero
if newVal > 0 {
upVals[upValIndex!] = newVal
upValIndex++
if upValIndex >= averageSize {
upValIndex = 0
}
}
if newVal < 0 {
downVals[downValIndex] =- newVal
downValIndex++
if downValIndex >= averageSize {
downValIndex = 0
}
}
// work out the average value above zero
var count: Float
var total: Float
for var i=0; i < averageSize; i++ {
if upVals[i] != invalidEntry {
count++
total+=upVals[i]
}
}
var averageUp = total/count
// and the average value below zero
count=0;
total=0;
for var i=0; i < averageSize; i++ {
if downVals[i] != invalidEntry {
count++
total+=downVals[i]
}
}
var averageDown = total/count
// is the new value a down value?
if newVal < (-0.5*averageDown) {
wasDown = true
}
// original Objective-C code
PulseDetector.h
#import <Foundation/Foundation.h>
#define MAX_PERIODS_TO_STORE 20 // is this an Int?
#define AVERAGE_SIZE 20 // is this a Float?
#define INVALID_PULSE_PERIOD -1 // done
#interface PulseDetector : NSObject {
float upVals[AVERAGE_SIZE];
float downVals[AVERAGE_SIZE];
int upValIndex;
int downValIndex;
float lastVal;
float periodStart;
double periods[MAX_PERIODS_TO_STORE]; // this is an array!
double periodTimes[MAX_PERIODS_TO_STORE]; // this is an rray !!
int periodIndex;
bool started;
float freq;
float average;
bool wasDown;
}
#property (nonatomic, assign) float periodStart; // var periodStart = float?
-(float) addNewValue:(float) newVal atTime:(double) time; // declaring a method called addNewValue with 2 arguments called atTime and time that returns a float
-(float) getAverage; // declaring a method called getAverage that returns a float
-(void) reset; // declaring a method that returns nothing
#end
PulseDetector.m
#import <QuartzCore/QuartzCore.h>
#import "PulseDetector.h"
#import <vector>
#import <algorithm>
#define MAX_PERIOD 1.5
#define MIN_PERIOD 0.1
#define INVALID_ENTRY -100 // is this a double?
#implementation PulseDetector
#synthesize periodStart;
- (id) init
{
self = [super init];
if (self != nil) {
// set everything to invalid
[self reset];
}
return self;
}
-(void) reset {
for(int i=0; i<MAX_PERIODS_TO_STORE; i++) {
periods[i]=INVALID_ENTRY;
}
for(int i=0; i<AVERAGE_SIZE; i++) {
upVals[i]=INVALID_ENTRY;
downVals[i]=INVALID_ENTRY;
}
freq=0.5;
periodIndex=0;
downValIndex=0;
upValIndex=0;
}
-(float) addNewValue:(float) newVal atTime:(double) time {
// we keep track of the number of values above and below zero
if(newVal>0) {
upVals[upValIndex]=newVal;
upValIndex++;
if(upValIndex>=AVERAGE_SIZE) {
upValIndex=0;
}
}
if(newVal<0) {
downVals[downValIndex]=-newVal;
downValIndex++;
if(downValIndex>=AVERAGE_SIZE) {
downValIndex=0;
}
}
// work out the average value above zero
float count=0;
float total=0;
for(int i=0; i<AVERAGE_SIZE; i++) {
if(upVals[i]!=INVALID_ENTRY) {
count++;
total+=upVals[i];
}
}
float averageUp=total/count;
// and the average value below zero
count=0;
total=0;
for(int i=0; i<AVERAGE_SIZE; i++) {
if(downVals[i]!=INVALID_ENTRY) {
count++;
total+=downVals[i];
}
}
float averageDown=total/count;
// is the new value a down value?
if(newVal<-0.5*averageDown) {
wasDown=true;
}
// is the new value an up value and were we previously in the down state?
if(newVal>=0.5*averageUp && wasDown) {
wasDown=false;
// work out the difference between now and the last time this happenned
if(time-periodStart<MAX_PERIOD && time-periodStart>MIN_PERIOD) {
periods[periodIndex]=time-periodStart;
periodTimes[periodIndex]=time;
periodIndex++;
if(periodIndex>=MAX_PERIODS_TO_STORE) {
periodIndex=0;
}
}
// track when the transition happened
periodStart=time;
}
// return up or down
if(newVal<-0.5*averageDown) {
return -1;
} else if(newVal>0.5*averageUp) {
return 1;
}
return 0;
}
-(float) getAverage {
double time=CACurrentMediaTime();
double total=0;
double count=0;
for(int i=0; i<MAX_PERIODS_TO_STORE; i++) {
// only use upto 10 seconds worth of data
if(periods[i]!=INVALID_ENTRY && time-periodTimes[i]<10) {
count++;
total+=periods[i];
}
}
// do we have enough values?
if(count>2) {
return total/count;
}
return INVALID_PULSE_PERIOD;
}
#end
Your problem is that you didn't copied the defines:
#define MAX_PERIODS_TO_STORE 20 // is this an Int?
#define AVERAGE_SIZE 20 // is this a Float?
#define INVALID_PULSE_PERIOD -1 // done
You have to change your defines so they work in your Swift code.
Check this answer how to replace the Objective-C #define to make Swift-Workable.
Also you could just change the defines to variables and initialize your variables with them.
First, a bit on optionals. Variables that end with a '?' are Optional, meaning that they are allowed to be nil (basically not exist). The compiler will not know at compile time whether this variable exists or not, because you are allowed to set it to nil.
"Unary operator '++' cannot be applied to an operand of type 'Int?'"
You seem to have read that last word as Int, but it is Int? which is significant. Basically, since it is an optional (as indicated by the question mark), the compiler knows it can be nil. You cannot use ++ on nil, and since optionals can be nil, you cannot use ++ on optionals. You must forcibly unwrap it first:
downValIndex!++ //note the exclamation point for unwrapping
"Use of unresolved identifier '=-'"
=- isnt a thing. -= is a thing. So
downVals[downValIndex] -= newVal
downVals[downValIndex] = downVals[downValIndex]-newVal //equivalent to above
"Binary operator '>=' cannot be applied to an operand of type 'Int? and Float'"
The compiler thinks you have an optional int on the left of the < and a Float on the right. Assuming you want two Ints, you must unwrap the left and make sure the right is cast to be an int (something like this). If you want two floats instead, cast or define as floats instead of ints.
if downValIndex! >= averageSize as! Int { //casting to Int
You should just be defining averageSize as an int though
var averageSize:Int = 10 //or whatever number
Also, you have lots of optionals. If any of them can be defined to something at compile time, it will make your life easier as you won't need to unwrap them everywhere. Alternately you could implicitly unwrap them (only do this if you are absolutely sure they will never be nil).
var implicitlyUnwrappedOptional:Int!
I am trying to write a code that will take two intergers, and will list all numbers lower than both of them except for those that are a factor of either if the two numbers inputted. At some point in my code though (see below) i am getting an error saying expected expression. I am a beginner so if you could explain this too me as simply as possible.
int main(int argc, const char * argv[])
{
#autoreleasepool {
int firstInterger;
int secondInterger;
int i;
printf("Please enter the first interger: ");
scanf("%i", &firstInterger);
printf("Please enter the second interger:");
scanf("%i", &secondInterger);
for (i = 0; i < firstInterger && i < secondInterger; i++) {
if ((firstInterger % i !== 0) && (secondInterger % i !== 0)) { //ERROR HERE!
printf("%i", i);
}
}
}
return 0;
}
You have twice the same error in that line.
You should replace !== with != or ==
const char *sentence = "He was not in the cab at the time.";
printf("\"%s\" has %d spaces\n", sentence, (int) ^ {
int i = 0;
int countSpaces = 0;
while (sentence[i] != '\0') {
if (sentence[i] == 0x20) {
countSpaces++;
}
i++;
}
return countSpaces;
});
This code simply counts the white space in a string, but for some reason it says 1606416608 spaces rather than 8. I'm not exactly sure what is going wrong, so thanks for any help!
You're passing the actual block to printf, not the result of the block. Instead, try
const char *sentence = "He was not in the cab at the time.";
printf("\"%s\" has %d spaces\n", sentence, (int) ^ {
int i = 0;
int countSpaces = 0;
while (sentence[i] != '\0') {
if (sentence[i] == 0x20) {
countSpaces++;
}
i++;
}
return countSpaces;
}()); // <-- note the extra parentheses here, indicating that you're calling the block