//Headers and libraries
    #include <stdio.h>
    #include <string.h>
    #include <stdlib.h>
    #include <math.h>
    #include <ctype.h>

//Comments // or /* */

//Types of variables     Bytes  Range(256^bytes)
    pointer                4    
    FILE                 148    
    void                   1    
    char                   1    //-127 a 127
    unsigned char          1    //0 a 255
    int                    4    //-2.147.483.648 a 2.147.483.647
    unsigned int           4    //0 a 4.294.967.295
    short int              4    //-32.768 a 32.767
    unsigned short int     2    //0 a 65.535 
    long int               4    //same int
    unsigned long int      4    //same int
    long long int          8    //same int
    unsigned long long int 8    //same int
    bool                   1    //0 a 1
    float                  4    //Six digits of precision
    double                 8    //Ten digits of precision
    long double           12    //Ten digits of precision

//Arithmetic operators
    Basic assignment =
    Addition         +
    Subtraction      -
    Multiplication   *
    Division         /
    Modulo           %
    var++;             //Suffix, the value of the variable is used and after incremented.
    --var;             //Prefix, the value is incremented and used after the command.
 
//Compound assignment operators
    var = var + var2;  ||  var += var2;
    var = var - var2;  ||  var -= var2;
    var = var * var2;  ||  var *= var2;
    var = var / var2;  ||  var /= var2;

//Comparison operators/relational operators
    Greater than             >
    Greater than or equal to >=
    Less than                <
    Less than or equal to    <=
    Equal to                 ==
    Not equal to             !=

//Logical operators
    Logical AND              &&
    Logical OR               ||
    Logical negation (NOT)    !

//Operator precedence
//Left-to-right
	Suffix increment, Suffix decrement, Function call
//Right-to-left
	Prefix increment, Prefix decrement,Logical NOT, Type cast, Indirection(*), Address-of(&), Size-of
//Left-to-right
	Multiplication, Division, Modulo, Addition, Subtraction, Less than, Less than or equal to, Greater than, Greater than or equal to, Equal to, Not, equal to, Logical AND, Logical OR
//Right-to-left
	Direct assignment(=), Assignment by sum(+=), by difference, by product, by quotient, by remainder
//Left-to-right
	Comma(,)

//Format specifiers
    "%c" Character.
    "%s" String of character.
    "%d" Decimal.
    "%i" Integer.
    "%u" Unsigned Decimal.
    "%e" Scientific notation, lowercase.
    "%E" Scientific notation, uppercase.
    "%f" Decimal floating point, lowercase.
    "%F" Decimal floating point, uppercase.
    "%g" Use the shortest representation: %e or %f.
    "%G" Use the shortest representation: %E or %F.
    "%o" Octal.
    "%x" Hexadecimal integer lowercase.
    "%X" Hexadecimal integer uppercase.
    "%a" Hexadecimal floating point, lowercase.
    "%A" Hexadecimal floating point uppercase.
    "%%" % followed by another % character will write a single %.
    "%p" Pointer address.

// Formatting codes
    New line    "\n"
    Tab         "\t"
    Backspace   "\b"
    Quotes      "\""
    Slash       "\\"
    Jump form   "\f"
    Null        "\0"

int printf ( const char * format, ...);//The total number of characters written is returned.
/*A format specifier follows this prototype:
%[flags][width][.precision][length]specifier 

Flags      Description
  -        Left-justify.
  +        Plus or minus sign (+ or -) even for positive numbers.

Width      Description
number     Minimum number of characters to be printed.
*          The width is not specified in the format string, but as an additional integer value.

precision  Description
.number    Precision specifies the minimum number of digits to be written or number of digits to be printed after the decimal point.
.*         The width is not specified in the format string, but as an additional integer value.
*/

int scanf ( const char * format, ...);//The function returns the number of items of the argument list successfully filled.
/*A format specifier follows this prototype:
%[*][width][length]specifier 

sub-specifier  Description
*              An optional starting asterisk indicates that the data is to be read from the stream but ignored.
width          Specifies the maximum number of characters to be read in the current reading operation.
*/

int fflush ( FILE * stream );//A zero value indicates success.
//If stream is a null pointer, all such streams are flushed.
//stdin  -> Standard input stream
//stdout -> Standard output stream
//stderr -> Standard error stream
int getchar ( void );//On success, the character read is returned (promoted to an int value).
//Returns the next character from the standard input (stdin).

    #include <stdio.h>
    int main(){
        int var;
        printf("Enter any value:");
	fflush(stdin); 
        scanf("%d",&var);
        printf("\nvar = %d",var);
        printf("\nThe double %d is %d",var,2*var);
	fflush(stdin);
	getchar();
        return 0;
    }

//if - else - else if

    if (condition) {
	/* Block to be executed if the condition is true */
    }
    else {
	/* Block to be executed if the condition is false */
    }

//switch - case

    switch (var) {
        case value_1:
            instructions;
            break;
        case value_n:
            instructions;
        break;
        default:
            instructions;;
 }

// ?:

 condition ? true : false

//while

    while (condition) {
        instructions;    
    }

//while infinite

    while (1) {
        instructions;    
    }

//do - while

    do{
        instructions; 
    }while (condition);

//for

    for (initializations, condition, increments) {
        instructions;
    }

//break and continue
    break;//Always causes program execution to continue at the first statement following the loop or block.
    continue; //Equates to reach the end of the block, the increments are performed and the condition is reevaluated.

//Exemplo vetor
    #include <stdio.h>

    int main(){
        int vetor[5],i;
        float media = 0;

        for(i = 0;i < 5;i++){
            printf("Vetor[%d]: ",i);
            scanf("%d",&vetor[i]);
        }

        for(i = 0;i < 5;i++){
            media =  media + vetor[i];
        }
        printf("\nMédia = %.1f",media/5);
        return 0;
    }

//Exemplo matriz
    #include <stdio.h>

    int main(){
        int matriz[3][3] = {00,01,02,10,11,12,20,21,22};
        int i,j;

        for(i = 0;i < 3;i++){
            printf("\n");
            for(j = 0;j < 3;j++){
                printf("%.2d ",matriz[i][j]);
            }
        }
        printf("\n");

        for(i = 0;i < 3;i++){
            printf("\n");
            for(j = 0;j < 3;j++){
                if(i == j){
                    printf("__ ");
                }
                else{
                    printf("%.2d ",matriz[i][j]);
                }
            }
        }
        printf("\n");

        for(i = 0;i < 3;i++){
            printf("\n");
            for(j = 0;j < 3;j++){
                if(i + j == 2){
                    printf("__ ");
                }
                else{
                    printf("%.2d ",matriz[i][j]);
                }
            }
        }
        printf("\n");

        for(i = 0;i < 3;i++){
            printf("\n");
            for(j = 0;j < 3;j++){
                if(i > j){
                    printf("__ ");
                }
                else{
                    printf("%.2d ",matriz[i][j]);
                }
            }
        }
        printf("\n");

        for(i = 0;i < 3;i++){
            printf("\n");
            for(j = 0;j < 3;j++){
                if(i < j){
                    printf("__ ");
                }
                else{
                    printf("%.2d ",matriz[i][j]);
                }
            }
        }
        printf("\n");

        return 0;
    }

//Exemplo string
    #include <stdio.h>
    #include <string.h>

    int main(){
        int i,aux=0;
        char letra,string[201];
        char letraA = 'a';
        char string1[101] = "string";
        char string2[101] = {'s','t','r','i','n','g','\0'};

        printf("String1: ");
        puts(string1);
        printf("String2: ");
        puts(string2);

        printf("\nDigite um caractere: ");
        letra = getchar();
        fflush(stdin);
        printf("Digite uma string: ");
        gets(string);

        printf("\nCaractere: ");
        putchar(letra);
        printf("\nString: ");
        puts(string);

        printf("Tamanho da string: %d\n",strlen(string));

        if(strcmp(string1,string2) == 0) printf("\nString1 == String2"); else printf("\nString1 != String2");

        strcpy(string1,"Um");
        strcpy(string2,"Dois");

        printf("\n\nString1: ");
        puts(string1);
        printf("String2: ");
        puts(string2);

        strcat(string,string1);
        strcat(string,string2);

        printf("\nString: ");
        puts(string);

        for(i = 0;i < strlen(string); i++){
            if (string[i] == letraA){
                aux++;
            }
        }
        printf("\nQuantidade de letras a na String: %d",aux);

        return 0;
    }

//Exemplo switch - case
    #include <stdio.h>

    int main(){
        int num;
        printf("Digite 1 para solteiro ou 2 para casado:\n");
        scanf("%d",&num);
        printf("\n");
        switch(num){
            case 1: printf("Solteiro"); break;
            case 2: printf("Casado"); break;
            default: printf("Valor invalido");
        }
        return 0;
    }

//Exemplo while
    #include <stdio.h>

    int main(){
        char tecla;

        while(tecla != 'a'){
            tecla = getchar();
        }
        return 0;
    }

//Exemplo do - while
    #include <stdio.h>

    int main(){
        int i=0;

        do{
            i++;
            printf("%d\t",i);
        }while(i < 10);
        return 0;
    }

// Variáveis locais e globais
    #include <stdio.h>
    int varGlobal;// Qualquer função pode acessá-la.

    main(){
        int varLocal;// Apenas a função main() tem acesso a esta variável.
    }

//Exemplo 1 Modularidade(Passagem por Valor)
    #include <stdio.h>

    float media(float a, float b, float c);

    int main(){
        float n1,n2,n3;

        printf("Digite três valores quaisquer: \n");
        scanf("%f%f%f",&n1,&n2,&n3);

        printf("\nMédia = %.1f",media(n1,n2,n3));
        return 0;
    }

    float media(float a, float b, float c){
        return (a + b + c) / 3;
        }

//Exemplo 2 Modularidade
    #include <stdio.h>
    float n1,n2,n3;
    void media();

    int main(){
        printf("Digite três valores quaisquer: \n");
        scanf("%f%f%f",&n1,&n2,&n3);
        media();
        return 0;
    }

    void media(){
        printf("\nMédia = %.1f",(n1 + n2 + n3) / 3);
    }

//Exemplo Ponteiros
#include <stdio.h>

    int main(){
        int a, *pa;
        a = 50;
        pa = &a; // pa recebe o endereço de a;

        printf("\nEndereço do ponteiro pa: %X", pa);
        printf("\nEndereço da variável contida no ponteiro pa: %X", &pa);
        printf("\nValor da variável contida no ponteiro pa: %d", *pa);

        return 0;
    }

//Exemplo 1 Parâmetro(Passagem de um valor por referência)
    #include <stdio.h>

    float media(float *a, float b, float c);

    int main(){
        float n1,n2,n3;

        printf("Digite três valores quaisquer: \n");
        scanf("%f%f%f",&n1,&n2,&n3);

        printf("\nMédia = %.1f",media(&n1,n2,n3));
        return 0;
    }

    float media(float *a, float b, float c){
        return (*a + b + c) / 3;
        }

//Exemplo 2 Parâmetro(Passagem e retorno por referência)
    #include <stdio.h>

    void media(float *a, float *b, float *c, float *retorno);

    int main(){
        float n1,n2,n3,aux;

        printf("Digite três valores quaisquer: \n");
        scanf("%f%f%f",&n1,&n2,&n3);

        media(&n1,&n2,&n3,&aux);

        printf("\nMédia = %.1f",aux);
        return 0;
    }

    void media(float *a, float *b, float *c, float *retorno){
        *retorno =  (*a + *b + *c) / 3;
        }

//Exemplo 3 Parâmetro(Vetor por referência)
    #include <stdio.h>

    void media(float *vetor, float *retorno);

    int main(){
        float v[3],aux;
        int i;

        for(i = 0; i < 3; i++){
            printf("v[%d]: ",i);
            scanf("%f",&v[i]);
        }

        media(v,&aux);

        printf("\nMédia = %.1f",aux);
        return 0;
    }

    void media(float *vetor, float *retorno){
        int i;
        float aux = 0;

        for(i = 0;i < 3; i++)
            aux += vetor[i];

        *retorno =  aux/3;
    }