- C Programming Tutorial
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Arrays allow to define type of variables that can hold several data items of the same kind. Similarly structure is another user defined data type available in C that allows to combine data items of different kinds.
You have seen the basic structure of a C program, so it will be easy to understand other basic building blocks of the C programming language. In a C program, the semicolon is a statement terminator. That is, each individual statement must be ended with a semicolon. It indicates the end of one.
Structures are used to represent a record. Suppose you want to keep track of your books in a library. You might want to track the following attributes about each book −
- Title
- Author
- Subject
- Book ID
Defining a Structure
To define a structure, you must use the struct statement. The struct statement defines a new data type, with more than one member. The format of the struct statement is as follows −
The structure tag is optional and each member definition is a normal variable definition, such as int i; or float f; or any other valid variable definition. At the end of the structure's definition, before the final semicolon, you can specify one or more structure variables but it is optional. Here is the way you would declare the Book structure −
Accessing Structure Members
To access any member of a structure, we use the member access operator (.). The member access operator is coded as a period between the structure variable name and the structure member that we wish to access. You would use the keyword struct to define variables of structure type. The following example shows how to use a structure in a program −
When the above code is compiled and executed, it produces the following result −
Structures as Function Arguments
You can pass a structure as a function argument in the same way as you pass any other variable or pointer.
When the above code is compiled and executed, it produces the following result −
Pointers to Structures
You can define pointers to structures in the same way as you define pointer to any other variable −
Now, you can store the address of a structure variable in the above defined pointer variable. To find the address of a structure variable, place the '&'; operator before the structure's name as follows −
To access the members of a structure using a pointer to that structure, you must use the → operator as follows −
Let us re-write the above example using structure pointer.
When the above code is compiled and executed, it produces the following result −
Bit Fields
Bit Fields allow the packing of data in a structure. This is especially useful when memory or data storage is at a premium. Typical examples include −
- Packing several objects into a machine word. e.g. 1 bit flags can be compacted.
- Reading external file formats -- non-standard file formats could be read in, e.g., 9-bit integers.
C allows us to do this in a structure definition by putting :bit length after the variable. For example −
Here, the packed_struct contains 6 members: Four 1 bit flags f1..f3, a 4-bit type and a 9-bit my_int.
C automatically packs the above bit fields as compactly as possible, provided that the maximum length of the field is less than or equal to the integer word length of the computer. If this is not the case, then some compilers may allow memory overlap for the fields while others would store the next field in the next word.
(Redirected from Middle c)
Middle C Play
C (Italian, French: Do) is the first note of the C majorscale, the third note of the A minor scale (the relative minor of C major), and the fourth note (F, A, B, C) of the Guidonian hand, commonly pitched around 261.63 Hz. The actual frequency has depended on historical pitch standards, and for transposing instruments a distinction is made between written and sounding or concert pitch.
In English the term Do is used interchangeably with C only by adherents of fixed-Do solfège; in the movable Do system Do refers to the tonic of the prevailing key.
- 2Octave nomenclature
- 5Scales
Frequency[edit]
Historically, concert pitch has varied. For an instrument in equal temperament tuned to the A440 pitch standard widely adopted in 1939, middle C has a frequency around 261.63 Hz (for other notes see piano key frequencies). Scientific pitch was originally proposed in 1713 by French physicist Joseph Sauveur and based on the numerically convenient frequency of 256 Hz for middle C, all C's being powers of two. After the A440 pitch standard was adopted by musicians, the Acoustical Society of America published new frequency tables for scientific use. A movement to restore the older A435 standard has used the banners 'Verdi tuning', 'philosophical pitch' or the easily confused scientific pitch.
Octave nomenclature[edit]
Middle C[edit]
Middle C (the fourth C key from left on a standard 88-key piano keyboard) is designated C4 in scientific pitch notation, the most commonly recognized in auditory science,[citation needed] while both C4 and the Helmholtz designation c′ are used in musical studies. Other note-octave systems, including those used by some makers of digital music keyboards, may refer to Middle C differently. In MIDI, Middle C is note number 60 which equates to C4.
While the expression Middle C is generally clear across instruments and clefs, some musicians naturally use the term to refer to the C note in the middle of their specific instrument's range. C4 may be called Low C by someone playing a Western concert flute, which has a higher and narrower playing range than the piano, while C5 (523.251 Hz) would be Middle C. This technically inaccurate practice has led some pedagogues to encourage standardizing on C4 as the definitive Middle C in instructional materials across all instruments.[1]
On the Grand Staff, middle-C is notated with a ledger line above the top line of the bass clef or below the bottom line of the treble clef.
Other octaves[edit]
In vocal music, the term High C (sometimes less ambiguously called Top C[2]) can refer to either the soprano's C6 (1046.502 Hz; c′′′ in Helmholtz notation) or the tenor's C5; both are written as the C two ledger lines above the treble clef but the tenor voice sings an octave lower. The term Low C is sometimes used in vocal music to refer to C2 because this is considered the divide between true basses and bass-baritones: a basso can sing this note easily, whereas other male voices, including bass-baritones, typically cannot.
Tenor C is an organ builder's term for small C or C3 (130.813 Hz), the note one octave below Middle C. In stoplists it usually means that a rank is not full compass, omitting the bottom octave.
Designation by octave[edit]
Scientific designation | Helmholtz designation | Octave name | Frequency (Hz) | Other names | Audio |
---|---|---|---|---|---|
C−1 | C͵͵͵ or ͵͵͵C or CCCC | Octocontra | 8.176 | Play | |
C0 | C͵͵ or ͵͵C or CCC | Subcontra | 16.352 | Play | |
C1 | C͵ or ͵C or CC | Contra | 32.703 | Play | |
C2 | C | Great | 65.406 | Low C, cello C, 8' C (see organ pipe length) | Play |
C3 | c | Small | 130.813 | 4' C or tenor C (organ), viola C | Play |
C4 | c′ | One-lined | 261.626 | Middle C | Play |
C5 | c′′ | Two-lined | 523.251 | Treble C, high C (written an octave higher for tenor voices)[3] | Play |
C6 | c′′′ | Three-lined | 1,046.502 | High C (soprano) | Play |
C7 | c′′′′ | Four-lined | 2,093.005 | Double high C[citation needed] | Play |
C8 | c′′′′′ | Five-lined | 4,186.009 | Eighth octave C, triple high C | Play |
C9 | c′′′′′′ | Six-lined | 8,372.018 | Quadruple high C | Play |
C10 | c′′′′′′′ | Seven-lined | 16,744.036 | Quintuple high C | Play |
(20,000 hertz is the start of the ultrasound in healthy young adults.)
Graphic presentation[edit]
Middle C in four clefs
Position of Middle C on a standard 88-key keyboard
Scales[edit]
Common scales beginning on C[edit]
- C Major: C D E F G A B C
- C Natural Minor: C D E♭ F G A♭ B♭ C
- C Harmonic Minor: C D E♭ F G A♭ B C
- C Melodic Minor Ascending: C D E♭ F G A B C
- C Melodic Minor Descending: C B♭ A♭ G F E♭ D C
Diatonic scales[edit]
- C Ionian: C D E F G A B C
- C Dorian: C D E♭ F G A B♭ C
- C Phrygian: C D♭ E♭ F G A♭ B♭ C
- C Lydian: C D E F♯ G A B C
- C Mixolydian: C D E F G A B♭ C
- C Aeolian: C D E♭ F G A♭ B♭ C
- C Locrian: C D♭ E♭ F G♭ A♭ B♭ C
Jazz melodic minor[edit]
- C Ascending Melodic Minor: C D E♭ F G A B C
- C Dorian ♭2: C D♭ E♭ F G A B♭ C
- C Lydian Augmented: C D E F♯ G♯ A B C
- C Lydian Dominant: C D E F♯ G A B♭ C
- C Mixolydian ♭6: C D E F G A♭ B♭ C
- C Locrian ♮2: C D E♭ F G♭ A♭ B♭ C
- C Altered: C D♭ E♭ F♭ G♭ A♭ B♭ C
B sharp[edit]
Comparison of notes derived from, or near, twelve perfect fifths (B♯)
Traversing the circle of fifths can result in a B♯ that is higher than C by 23.46 cents, the ratio of twelve just perfect fifths (B♯) to seven octaves being 531,441 / 524,288, the Pythagorean comma. A B♯ that is three just major thirds above C is lower than the octave by an interval called a diesis, 125:128 or 41.06 cents.
See also[edit]
References[edit]
- ^Large, John (February 1981). 'Theory in Practice: Building a Firm Foundation'. Music Educators Journal. 32: 30–35.
- ^Harold C. Schonberg (November 4, 1979). 'Birgit Nilsson – The Return of a Super-Soprano'. The New York Times.
- ^'Luciano Pavarotti – King of the High C's', The New York Times', September 9, 2007
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