c prog Cheat Sheet

A cheat sheet in English by TheAwesomeLoner

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PRs

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File managment exs

{
FILE *fp;
char ch;
fp = fopen("one.txt", "w");
printf("Enter data...");
while( (ch = getchar()) != EOF) {
putc(ch, fp);
}
fclose(fp);
fp = fopen("one.txt", "r");

while( (ch = getc(fp)! = EOF)
printf("%c",ch);

// closing the file pointer
fclose(fp);

return 0;
}

stucture

struct Books {	struct Books Book1;
char title[50];	strcpy( Book2.title, "Telecom Billing");
char author[50];	strcpy
char subject[100];	dest − This is the pointer to the destination array where the content is to be copied.
int book_id;	src − This is the string to be copied.
} book;

qsort

void qsort(void base, size_t nitems, size_t size, int (compar)(const void , const void))
base − This is the pointer to the first element of the array to be sorted.

nitems − This is the number of elements in the array pointed by base.

size − This is the size in bytes of each element in the array.

compar − This is the function that compares two elements.

File managment functions

fopen() create a new file or open a existing file	a opens a text file in append mode
fclose() closes a file	w opens or create a text file in writing mode.
getc() reads a character from a file	r opens a text file in reading mode
putc() writes a character to a file
fscanf() reads a set of data from a file
fprintf() writes a set of data to a file

array search

int main()
{
int array[100], search, c, n;

printf("Enter the number of elements in array\n");
scanf("%d",&n);

printf("Enter %d integer(s)\n", n);

for (c = 0; c < n; c++)
scanf("%d", &array[c]);

printf("Enter the number to search\n");
scanf("%d", &search);

for (c = 0; c < n; c++)
{
if (array[c] == search) / if required element found /
{
printf("%d is present at location %d.\n", search, c+1);
break;
}
}
if (c == n)
printf("%d is not present in array.\n", search);

return 0;
}

c - bits manipulation

&	Binary AND Operator copies a bit to the result if it exists in both operands.	(A & B) will give 12 which is 0000 1100
\|	Binary OR Operator copies a bit if it exists in eather operand.	(A \| B) will give 61 which is 0011 1101
^	Binary XOR Operator copies the bit if it is set in one operand but not both.	(A ^ B) will give 49 which is 0011 0001
~	Binary Ones Complement Operator is unary and has the efect of 'flipping' bits.	(~A ) will give -60 which is 1100 0011
<<	Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand.	A << 2 will give 240 which is 1111 0000

char array

char p[] = "hello"

char *p = "hello"

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