int procurarMatriculaLista(tipoEspera listaDeEspera[], int ClistaDeEspera, char matricula[])
{
int i, pos= -1;
for(i = 0; i<ClistaDeEspera; i++)
{
printf("coock");
if(strcmp(listaDeEspera[i].matricula, matricula) == 0)
{
pos=i;
i=ClistaDeEspera;
}
}
return pos;
}
It has no errors but my program crashes whenever I call this function. Why?
If it's crashing in that function, the most likely cause is that the arguments being given to strcmp are causing it to fail. Such as if they're not actually C-style strings, or if the length value (ClistaDeEspera) you're passing in is too big for the actual array.
Hence you need to check listaDeEspera[i].matricula where i ranges from 0 to ClistaDeEspera - 1 inclusive, and matricula.
Most likely one of those values is not what you think it is.
As an aside, your code could be made "cleaner" by getting rid of the store-position-and-force-loop-end aspect. With a small piece of code like this, multiple return points have no real detrimental affect on readability:
int procurarMatriculaLista(tipoEspera listaDeEspera[], int ClistaDeEspera, char matricula[]) {
for (int i = 0; i < ClistaDeEspera; i++)
if (strcmp (listaDeEspera[i].matricula, matricula) == 0)
return i;
return -1;
}
Related
trying to copy stuff from b into a but i get that error
someone told me it means i'm trying to access memory that i'm not allowed to, but i don't know what should i do to make it compile.
replace(txt , code);
string replace(string a , string b)
{
string alpha[26] = {"abcdefghijklmnopqurstuvwxyz"};
for (int i = 0; i < strlen(a); i++)
{
for(int n = 0; n < 26; n++)
{
if(a[i] == alpha[n])
{
a[i] = b[n];
i++;
}
}
}
return word;
}
i'm a beginner so no comments about clean coding or syntactic sugar or stuff like that just help me resolve this please
It looks like you have some problems with understending pointers, so I recommend you to read about them. Also consider reading about datatypes and types from STL you are using. (cause std::string is already an array of values so, when you are creating std::string[26], you actually are creating pointer to a pointer)
I guess you have are trying to do something like that:
std::string replace(string a , string b)
{
std::string alpha = {"abcdefghijklmnopqurstuvwxyz"};
for (size_t i = 0; i < a.size(); ++i)
{
for(size_t n = 0; n < alpha.size(); ++n)
{
if(a[i] == alpha[n])
{
a[i] = b[n];
i++; // Also, I think you doesnt need this line, cause you already incrementing i in for loop
}
}
}
return a;
}
Also you have used strlen() on your string, that also is not really correct, cause it is used on char values. If you whant to get length of a string it is better to use string.lenght()
Also, It is better to use size_t or unsigned int instead of int in this case, cause you don't need negative numbers in order to parce these strings. ()
This function is basically just supposed to compare 2 strings and return their ASCII difference if they are different. It works perfectly fine when I compile it with the GCC compiler, but when I run it through the online compiler that is used to upload our classes homework, I get this error message:
Error near line 98: Reading an uninitialized value from address 10290
Line 98 is marked in the below code. I am not quite sure what the problem is and how I'm supposed to fix it. Does anyone have an idea?
int stringCompare(char * pStr1, char * pStr2) {
int n = 100;
int difference;
for (int i = 0; i < n; i++) {
difference = pStr1[i] - pStr2[i]; // line 98
if (difference != 0) {
return difference;
}
}
return difference;
}
Your code can skip over EOLN, if string equals, and try to compare memory after end of lines. To fix this, you need instantly return, if both string equals, and you see EOLN char '\0' in both strings at position i. Try my fix:
int stringCompare(char * pStr1, char * pStr2) {
int n = 100;
int difference;
for (int i = 0; i < n; i++) {
difference = pStr1[i] - pStr2[i];
if (difference != 0 || pStr1[i] == '\0') {
return difference;
}
}
return difference;
}
The problem in your code is that you fail to check the real length of the strings before indexing them. You are iterating with i from 0 to 99, but you do not check for the NUL terminator (\0) that marks the end of a string and therefore your for loop goes beyond the end of the string resulting in undefined behavior accessing memory that is not supposed to (which is what the error is telling you).
The correct way to iterate over a string, is not to loop a fixed amount of cycles: you should start from index 0 and check each character of the string in the loop condition. When you find \0, you stop. See also How to iterate over a string in C?.
Here's a correct version of your code:
int stringCompare(char *pStr1, char *pStr2) {
size_t i;
for (i = 0; pStr1[i] != '\0' && pStr2[i] != '\0'; i++) {
if (pStr1[i] != pStr2[i])
break;
}
return pStr1[i] - pStr2[i];
}
You could even write this more concisely with a simple while loop:
int stringCompare(char *pStr1, char *pStr2) {
while (*pStr1 && *pStr1 == *pStr2) {
pStr1++;
pStr2++;
}
return *pStr1 - *pStr2;
}
Of course, both the above functions expect two valid pointers to be passed as arguments. If you also want to allow invalid pointers you should check them before starting the loop (though it does not seem like you want to do that from your code).
I've tried this code but it doesn't seem to be working, how to break out of the nested loop ?
#include <stdio.h>
#include <string.h>
int meme(char s1[], char s2[])
{
int i = 0, j = 0;
int different;
while (i <= strlen(s1) && different == 1) {
while (j <= strlen(s2)) {
if (s1[i] != s2[j]) {
different = 1;
} else {
different = 0;
}
j = j + 1;
}
i = i + 1;
}
return different;
}
You have to initialize different as it is undefined if not - this probably breaks your first while loop as different probably is a random number > 1.
strlen gives you the number of characters in the string excluding the null-character which terminates the string (see here). However, you do not only compare the characters of the two strings, but also the null-character, probably to implicitely check if the length of the strings is the same. While this should work, it is better to do this check explicitely by comparing the length of the strings first as it is less error-prone.
It isn't necessary to do a nested loop here if you compare the length of the strings first. Also, you now know the length of both strings, so this function can be change to use a for loop, which makes it even simpler.
A possible solution based on the points above:
#include <stdio.h>
#include <string.h>
int meme(char s1[], char s2[]){
int i = 0;
int len_s1 = 0;
int len_s2 = 0;
int different = 0;
len_s1 = strlen(s1);
len_s2 = strlen(s2);
if (len_s1 == len_s2) {
for (i = 0 ; i < len_s1 ; i++) {
if (s1[i] != s2[i]) {
different = 1;
break;
}
}
else {
different = 1;
}
return different;
}
One more thing - do yourself and everyone else a favor and intend your code as it is extremely hard to read otherwise!
Your code is not optimized and you are not using a good approach for doing the task. I have modified the code and it will do the job with minimized complexity.
Here I assume that both the arrays are of same size as your problem shows
bool meme(char s1[], char s2[])
{
int i=0;
while(s1[i] != NULL && s2[i] != NULL)
{
if(s1[i] == s2[i])
return false;
i += 1;
}
return true;
}
When you call this function then declare a variable of type bool and store the returned value of this function in that variable.
For example :
bool check;
bool = meme(array 1 , array 2);
and then check if returned value is true, then both the arrays are totally different else not. You can do that by the below code :
if(check)
printf("Arrays are different");
else
printf("Arrays are not different");
You can also use int in place of bool if it suits you better but remember, whatever code you write, must be least complex. And think that if you are using int then also you are returning only 0 or 1; but int takes 2 bytes in 32-bit compiler and 4 bytes in 64-bit compiler, but bool takes only 1 byte and even 1 bit in some languages like pascal (if I am not wrong).
And don't get confused with return true; and return false;. True simply means 1 and false means 0. And a boolean type variable can store only binary number (1 or 0).
There is so much wrong with your code.
Why are you calling strlen() in while()? It will get executed every time till the loop doesn't exit and will cost on performance.
Also the variable different is not initialized with value 1, so how can you be so sure about the initial value of that variable?
I have tried to simplify your function still, there is scope for optimization:
int meme(char s1[], char s2[])
{
int i = 0;
int different;
int str1_len = strlen(s1);
int str2_len = strlen(s2);
if(str1_len > str2_len)
str1_len = str2_len;
do{
if(s1[i] == s2[i])
{
printf("Common\n");
different = 0;
}
else
{
different = 1;
}
i++;
}while(str1_len--);
return different;
}
I want to remove any spaces from the user input and give the result back on the screen. So far, the following is my working solution. I haven't noticed any errors yet. Since I'm pretty new to C and programming in general, my question is: Is there something I can do better? Anything to optimize or something? I appreciate any tips from you guys since you are probably a lot more experienced than I am. So, here's my code:
#include <stdio.h>
#include <string.h>
#define PUFFERGROESSE 100
#define ERROR 1
#define OK 0
int main(){
char stringPuffer[PUFFERGROESSE];
printf("Please enter some words:"); fflush(stdout);
if(fgets(stringPuffer, PUFFERGROESSE, stdin) == NULL){
printf("Unable to read.\n");
return ERROR;
} else {
char endString[PUFFERGROESSE];
for (int i = 0, j = 0; i < PUFFERGROESSE; i++, j++) {
if (stringPuffer[i] != ' ' ) {
endString[j] = stringPuffer[i];
} else {
j--;
}
}
printf("Without spaces your input looks like that: %s", endString);
}
}
In your code, the for loop condition is i < PUFFERGROESSE. Inside this loop, you access stringPuffer using the loop index.
Now, stringPuffer being an uninitialized automatic local variable and with a sufficiently small input, a strict check like i < PUFFERGROESSE will cause access to uninitialized memory of stringPuffer, creating undefined behavior.
You can make use of strlen() after taking the user input.
Another note, int main() is better as int main(void), at least.
NITPICK: why's the OK defined, if not used?
Several suggestions:
Initialize endString to all zeros; that way you won't have to worry about string termination issues later on:char endString[PUFFERGROESSE] = {0};
Instead of looping while i is less than PUFFERGROESSE, loop until you see the end of the string:for( int i = 0, j = 0; stringPuffer[i] != 0; i++ )
Also, only increment j when you write the non-space character, rather than incrementing it unconditionally and then having to decrement it when you see a space:if ( !isspace( stringPuffer[i] ) )
endString[j++] = stringPuffer[i];
So basically, that code reduces to:
char endString[PUFFERGROESSE] = {0};
for (int i = 0, j = 0; stringPuffer[i] != 0; i++) {
if ( !isspace( stringPuffer[i] ) ) {
endString[j++] = stringPuffer[i];
}
}
typedef struct _set{
int root;
int rank;
}Set;
void Kruskal(Graph* g)
{
Set uni[g->nv];
Edge result[g->nv - 1];
int i;
int count = 0;
int num = 0;
int aRoot, bRoot;
for(i = 0; i < g->nv; i++){
uni[i].root = i;
uni[i].rank = 0;
}
QuickSort(g, 0, g->ne-1);
while(count != (g->nv-1) && num != g->ne){
WeightedUnion(uni, g->path[num].src, g->path[num].dest);
aRoot = Find(uni, g->path[num].src);
bRoot = Find(uni, g->path[num].dest);
if( aRoot != bRoot){
result[num] = g->path[num];
count++;
}
num++;
}
if(count != g->nv-1){
printf("No spanning tree\n");
}
else{
for(i = 0; i <= count; i++){
printf("[%d] %d - %d : %d\n",i+1,result[i].src,result[i].dest,result[i].weight);
}
}
}
This is my part of code. The problem is that I can't initialize 'uni[g->nv]'. You can see 'for' loop next to the variable area. And I was sure about that reputation must initialize this array but a result was not. That array didn't include any other values. just empty. I cannot find my problem. Please tell me my problem or mistakes.
I run my code in Xcode. Maybe this information is helpful
You are using a variable length array (VLA), that is an array with a length that depends dynamically on an expression during run time. Since the size is not known at compile time, you can't initialize them with an initializer expression, but must do it with a for loop as you are doing.
VLA are usually realized when your program executes on the so-called stack of the function in which it is defined. That stack has a size limit and you have to be careful that you don't overrun it. (And if you do, there is no tool to know directly.)
So don't use VLA as you do for big data of unknown size. Instead, use a pointer and malloc to allocate the memory that you need.