Converting buffer to array of strings-CodePudding

I downloaded text from edit field to buffer and i want to convert it to a array of strings. Every string is ending with "%".

void Converter(HWND hwnd)
{
    int Length = GetWindowTextLength(hEdit)   1;
    LPSTR data = (LPSTR)malloc(Length);
    char set[500][11];

    GetWindowTextA(hEdit, data, Length);

    int x = 0, y = 0;
    char record[10];
    
    for (int i = 0; i < Length, x<500; i  )
    {
        if(data[i]!= '\0' )
            {
            record[y] = data[i];
            y  ;
            }
        else if(data[i] == '%')
        {
            strcpy(set[x], record);
            x  ;
            y = 0;
        }
    }
    free(data);
}

The error message i get is this:

Exception thrown at location 0x00007FF684C91F9B in myproject.exe: 0xC0000005: Access violation while reading at location 0x000000CBFC8D5DAF.

Please be easy on me

CodePudding user response：

The problem is in this line

for (int i = 0; i < Length, x<500; i  )

Your condition is wrong, it should be:

for (int i = 0; i < Length && x<500; i  )

Also, the else if block is never executed, because '%' is not equal to '\0'. This can be fixed by swapping them.

if(data[i] == '%')
{
    strcpy(set[x], record);
    x  ;
    y = 0;
}
else if(data[i] != '\0')
{
    record[y] = data[i];
    y  ;
}

The third problem is that the last word in your %-delimited string will not be copied into set since there is no percent sign after it.

There is one more bug. You forgot to put a null-terminator at the end of record before copying it, this causes shorter strings to retain letters from previous ones.

record[y] = '\0';
strcpy(set[x], record);

At this point I recommend using strtok from <string.h>, and a memory safe programming language like Rust, because C is too dangerous in your hands.

CodePudding user response：

Sample code to show strcpy with 2d array is use:

#include <stdio.h>

int main() {
   
    char set[500][11];
    
    strcpy(&set[x][0], "a record");

    printf(">> %s", &set[x][0]);
}

Output:

>> a record

CodePudding user response：

you can do like this

char** make_array(_In_ char* buf, _Out_ unsigned* pn)
{
    char* pc = buf;
    unsigned n = 1;
    
    while(pc = strchr(pc, '%')) n  , *pc   = 0;

    if (char** arr = new char*[n])
    {
        *pn = n;

        char** ppc = arr;
        
        do {
            *ppc   = buf;
            buf  = strlen(buf)   1;
        } while(--n);

        return arr;
    }

    *pn = 0;
    return 0;
}

void demo()
{
    char buf[] = "1111"223333";
    unsigned n;
    if (char** arr = make_array(buf, &n))
    {
        char** ppc = arr;
        do {
            printf("%s\n", *ppc  );
        } while (--n);
        delete [] arr;
    }
}