Practical Test Reminders, Character Arrays, C-Strings

Printing a Character Array

Printing blocks of text (%s) C-String

print from the array specified, until it finds an element in the char array that has the value 0

C-Strings: a collection of characters is often referred to as a “string”

In C, strings are expected to be null terminated (C-Strings must be null terminated)

Meaning they end with the null character (The literal for this is: ‘\0’) (This is the value 0.)

We will call these C-Strings.

Remember:

Any other type of array is not terminated with a zero

Char arrays that contain C-Strings are terminated with a zero (the null character)

In initialization way

Initialized by using a simpler notation

It is printed as normal variables by combination of printf.

Beware the difference between %c (single char) and %s(string, array of char)

Character Array Sizes

Use scanf and %s to read into a char array by only one scanf

(don not need to scanf one char by one char unlike %c)

The array must be big enough to hold the number of characters

Restrict scanf to only read in the next 10 chars from input

%10s

Scansets

specify scanset specifiers with scanf by using % [ ]

Inside the [ ] brackets, we can specify the characters that scanf will process (or parse)

[A-Z]

(Stop scanning into the array when the next item in the input stream buffer is not an uppercase character…)

[A-Za-z]

(top scanning into the array when the next item in the input stream buffer is not an uppercase or lowercase character)

[0-9]

(Stop scanning into the array when the next item in the input stream buffer is not a digit character…)

…….

[^\n]

(Stop scanning when the user presses enter)

scanf("%*[^\n]");

*means scanf a something(here means” \n”), but do not save to the variables or array.

Means: scanf every char except the “\n”

C-String Length

#include <string. h>to access the strlen function

strlen takes in a char array and returns the number of characters in the C-String

The length of a C-String is not the same as the size of the char array in which it is stored (whitespace also be counted)

C-String Copying

#include <string. h>to access the strcpy function

strcpy takes in two char array parameters, the first one is the destination to copy to, the second one is the source to copy from.

C-String Concatenation

#include <string. h>to access the strcat function

char arrays that contain C-Strings are terminated with a zero

C-String convert to an int

atoi ()

convert a number, encoded as ASCII characters

atoi stands for “ASCII to int”

atof ()

converting ASCII text into a floating-point number

stands for “ASCII to floating-point”

Printing into a char Array

sprintf()

The array can then be used later… and then perhaps printed to the screen

sprintf needs to know what array to print into, and then the formatted string literal to print, followed by the variables

To convert an integer number into a C-String

(the char array must be big enough to hold all the ASCII digits)

If convert to float change the %d to %f

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