You're saying you have this:
char array[20]; char string[100];
array[0]='1';
array[1]='7';
array[2]='8';
array[3]='.';
array[4]='9';
And you'd like to have this:
string[0]= "178.9"; // where it was stored 178.9 ....in position [0]
You can't have that. A char holds 1 character. That's it. A "string" in C is an array of characters followed by a sentinel character (NULL terminator).
Now if you want to copy the first x characters out of array to string you can do that with memcpy():
memcpy(string, array, x);
string[x] = '\0';
You're saying you have this:
char array[20]; char string[100];
array[0]='1';
array[1]='7';
array[2]='8';
array[3]='.';
array[4]='9';
And you'd like to have this:
string[0]= "178.9"; // where it was stored 178.9 ....in position [0]
You can't have that. A char holds 1 character. That's it. A "string" in C is an array of characters followed by a sentinel character (NULL terminator).
Now if you want to copy the first x characters out of array to string you can do that with memcpy():
memcpy(string, array, x);
string[x] = '\0';
Assuming array is a character array that does not end in \0, you will want to use strncpy:
char * strncpy(char * destination, const char * source, size_t num);
like so:
strncpy(string, array, 20);
string[20] = '\0'
Then string will be a null terminated C string, as desired.
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Hello everyone!
In this simple example, how can I replace the new_key string contents with the uppercase of the key string? I can print it alright with the below code, but can't find a way to store the characters in the empty string - there are always either segmentation fault errors or initializer ones.
What would be the best way to make new_key[i] be the content of toupper(key[i])?
#include <stdio.h>
#include <cs50.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
int main(void)
{
string key = "abcde";
string new_key[] = "";
for (int i = 0, len = strlen(key); i < len; i++)
{
char c = key[i];
printf("%c", toupper(c));
}
}
I know that a string is already technically an array of chars, but when I try to use toupper(string), it doesn’t work because toupper is designed to capitalize chars and not strings, per the documentation. I’ve been making it overly complicated and it’s stressing me out. So to start, I created an “int N=strlen(string);”, then created an array that’s “char upper[N];”. Then I write a for loop written as(please forgive the terrible syntax I’m about to write), “for (int i = 0; i < N; i++) { toupper(upper[j]); }”. What am I doing wrong?
In C, a string is actually stored as an array of characters, so the 'string pointer' is pointing to the first character. For instance,
char myString[] = "This is some text";
You can access any character as a simple char by using myString as an array, thus:
char myChar = myString[6];
printf("%c\n", myChar); // Prints s
Hope this helps! David
In C, there's no (real, distinct type of) strings. Every C "string" is an array of chars, zero terminated.
Therefore, to extract a character c at index i from string your_string, just use
char c = your_string[i];
Index is base 0 (first character is your_string[0], second is your_string[1]...).
Hi everyone, so I'm learning the basics of C using some online resources, and came across the following example of using a char pointer array:
const int MAX = 4;
int main (){
char *names[] = {
"Zara Ali",
"Hina Ali",
"Nuha Ali",
"Sara Ali"
};
int i = 0;
for ( i = 0; i < MAX; i++) {
printf("Value of names[%d] = %s\n", i, names[i] );
}
return 0;
}
And I just can't understand why making it an array (and not a pointer array) won't work, aka why just removing the * results in an error while running the code.
Could someone please dumb it down for me?