C Tutorial Examples
C library function wcstombs() example
#include <stdio.h>
#include <stdlib.h>
#define BUFFER_SIZE 50
int main () {
size_t ret;
char *MB = (char *)malloc( BUFFER_SIZE );
wchar_t *WC = L"Welcome To Tutorialsroot.com";
/* converting wide-character string */
ret = wcstombs(MB, WC, BUFFER_SIZE);
printf("Characters converted = %u\n", ret);
printf("Multibyte character = %s\n\n", MB);
return(0);
}
Output
Characters converted = 28
Multibyte character = Welcome To Tutorialsroot.com
C library function malloc() example
#include <stdio.h>
#include <stdlib.h>
int main () {
char *str;
/* Initial memory allocation */
str = (char *) malloc(15);
strcpy(str, "tutorialsroot");
printf("String = %s, Address = %u\n", str, str);
/* Reallocating memory */
str = (char *) realloc(str, 25);
strcat(str, ".com");
printf("String = %s, Address = %u\n", str, str);
free(str);
return(0);
}
Output
String = tutorialsroot, Address = 35287056
String = tutorialsroot.com, Address = 35291200
C library function atan() example
#include <stdio.h>
#include <math.h>
#define PI 3.141592654
int main()
{
double num = 1.0;
double result;
result = atan(num);
printf("Inverse of tan(%.2f) = %.2f in radians", num, result);
// Converting radians to degrees
result = (result * 180) / PI;
printf("\nInverse of tan(%.2f) = %.2f in degrees", num, result);
return 0;
}
Output
Inverse of cos(1.00) = 0.79 in radians
Inverse of cos(1.00) = 45 in degrees
C library function time() example
#include <stdio.h>
#include <time.h>
int main () {
time_t seconds;
seconds = time(NULL);
printf("Hours since January 1, 1980 = %ld\n", seconds/3600);
return(0);
}
Output
Hours since January 1, 1980 = 425190
C library function strftime() example
#include <stdio.h>
#include <time.h>
int main () {
time_t rawtime;
struct tm *info;
char buffer[80];
time( &rawtime );
info = localtime( &rawtime );
strftime(buffer,80,"%x - %I:%M%p", info);
printf("Formatted date & time : |%s|\n", buffer );
return(0);
}
Output
Formatted date & time : |07/04/18 - 06:46AM|
C library function localtime() example
#include <stdio.h>
#include <time.h>
int main () {
time_t rawtime;
struct tm *info;
char buffer[80];
time( &rawtime );
info = localtime( &rawtime );
printf("Current local time and date: %s", asctime(info));
return(0);
}
Output
Current local time and date: Wed Jul 4 06:51:23 2018
C library function gmtime() example
#include <stdio.h>
#include <time.h>
#define PDT (-7)
int main(int argc, const char * argv[])
{
/* Define temporary variables */
struct tm *gtime;
time_t now;
/* Read the current system time */
time(&now);
/* Convert the system time to GMT (now UTC) */
gtime = gmtime(&now);
/* Display the time in PDT and UTC */
printf ("Pacific Daylight Time: %2d:%02d\n", (gtime->tm_hour + PDT) % 24,
gtime->tm_min);
printf ("Universal Time: %2d:%02d\n", gtime->tm_hour % 24, gtime->tm_min);
return 0;
}
Output
Pacific Daylight Time: 14:14
Universal Time: 21:14
C library function difftime() example
#include <iostream>
#include <ctime>
using namespace std;
int main()
{
time_t start, finish;
long product;
time(&start);
for(int i=0; i<10000; i++)
{
for(int j=0; j<100000; j++)
{
product = i*j;
}
}
time(&finish);
cout << "Time required = " << difftime(finish, start) << " seconds";
return 0;
}
Output
Time required = 3 seconds
C library function ctime() example
#include <iostream>
#include <ctime>
using namespace std;
int main()
{
time_t curr_time;
curr_time = time(NULL);
char *tm = ctime(&curr_time);
cout << "Today is : " << tm;
return 0;
}
Output
Today is : Fri Mar 24 18:48:04 2017
C library function clock() example
#include <time.h>
#include <stdio.h>
int main () {
clock_t start_t, end_t, total_t;
int i;
start_t = clock();
printf("Starting of the program, start_t = %ld\n", start_t);
printf("Going to scan a big loop, start_t = %ld\n", start_t);
for(i=0; i< 10000000; i++) {
}
end_t = clock();
printf("End of the big loop, end_t = %ld\n", end_t);
total_t = (double)(end_t - start_t) / CLOCKS_PER_SEC;
printf("Total time taken by CPU: %f\n", total_t );
printf("Exiting of the program...\n");
return(0);
}
Output
Starting of the program, start_t = 660
Going to scan a big loop, start_t = 660
End of the big loop, end_t = 28739
Total time taken by CPU: 0.000000
Exiting of the program...
C library function asctime() example
#include <stdio.h>
#include <string.h>
#include <time.h>
int main () {
struct tm t;
t.tm_sec = 20;
t.tm_min = 20;
t.tm_hour = 6;
t.tm_mday = 25;
t.tm_mon = 2;
t.tm_year = 89;
t.tm_wday = 6;
puts(asctime(&t));
return(0);
}
Output
Sat Mar 25 06:20:20 1989
C library function strxfrm() example
#include <iostream>
#include <cstring>
#include <clocale>
using namespace std;
int main()
{
setlocale(LC_COLLATE, "cs_CZ.UTF-8");
const char* s1 = "hrnec";
const char* s2 = "chrt";
char t1[20], t2[20];
cout << "strcoll returned " << strcoll(s1,s2) << endl;
cout << "Before transformation, " << "strcmp returned " << strcmp(s1,s2) << endl;
strxfrm(t1,s1,10);
strxfrm(t2,s2,10);
cout << "After transformation, " << "strcmp returned " << strcmp(t1,t2) << endl;
return 0;
}
Output
strcoll returned -1
Before transformation, strcmp returned 1
After transformation, strcmp returned -1
C library function strtok() example
#include <cstring>
#include <iostream>
using namespace std;
int main()
{
char str[] = "Crimson Chat,Tropical Parula,sparrow,pigeon,crow";
char delim[] = ",";
cout << "The tokens are:" << endl;
char *token = strtok(str,delim);
while (token)
{
cout << token << endl;
token = strtok(NULL,delim);
}
return 0;
}
Output
The tokens are:
Crimson Chat
Tropical Parula
sparrow
pigeon
crow
C library function strstr() example
#include <stdio.h>
#include <string.h>
int main () {
const char haystack[20] = "TutorialsRoot";
const char needle[10] = "Root";
char *ret;
ret = strstr(haystack, needle);
printf("The substring is: %s\n", ret);
return(0);
}
Output
The substring is: Root
C library function strspn() example
#include <cstring>
#include <iostream>
using namespace std;
int main()
{
char src[] = "0123456789";
char dest[] = "190126abqs121kfew";
size_t length = strspn(dest, src);
cout << dest << " contains " << length << " initial numbers";
return 0;
}
Output
190126abqs121kfew contains 6 initial numbers
C library function strrchr() example
#include <stdio.h>
#include <string.h>
int main () {
int len;
const char str[] = "http://www.tutorialsroot.com";
const char ch = '.';
char *ret;
ret = strrchr(str, ch);
printf("String after |%c| is - |%s|\n", ch, ret);
return(0);
}
Output
String after |.| is - |.com|
C library function strpbrk() example
#include <iostream>
#include <cstdio>
using namespace std;
int main()
{
char digits[] = "0123456789";
char code[] = "ceQasieoLPqa4xz10Iyq";
char *pos;
int count = 0;
pos = strpbrk (code, digits);
while (pos != NULL)
{
pos = strpbrk (pos+1,digits);
count ++;
}
cout << "There are " << count << " numbers in " << code;
return 0;
}
Output
There are 3 numbers in ceQasieoLPqa4xz10Iyq
C library function strlen() example
#include <stdio.h>
#include <string.h>
int main()
{
char a[20]="Program";
char b[20]={'P','r','o','g','r','a','m','\0'};
char c[20];
printf("Enter string: ");
gets(c);
printf("Length of string a = %d \n",strlen(a));
//calculates the length of string before null charcter.
printf("Length of string b = %d \n",strlen(b));
printf("Length of string c = %d \n",strlen(c));
return 0;
}
Output
Enter string: String
Length of string a = 7
Length of string b = 7
Length of string c = 6
C library function strerror() example
#include <stdio.h>
#include <string.h>
#include <errno.h>
int main () {
FILE *fp;
fp = fopen("file.txt","r");
if( fp == NULL ) {
printf("Error: %s\n", strerror(errno));
}
return(0);
}
Output
Error: No such file or directory
C library function strcspn() example
#include <stdio.h>
#include <stdlib.h>
int main() {
int size;
// initializing strings
char str1[] = "tutorialsroot";
char str2[] = "kfc";
// using strcspn() to calculate initial chars
// before 1st matching chars.
// returns 3
size = strcspn(str1, str2);
printf("The unmatched characters before first matched character : %d\n", size);
}
Output
The unmatched characters before first matched character : 3
C library function strncpy() example
#include <stdio.h>
#include <stdlib.h>
int main () {
char src[40];
char dest[12];
memset(dest, '\0', sizeof(dest));
strcpy(src, "This is tutorialsroot.com");
strncpy(dest, src, 10);
printf("Final copied string : %s\n", dest);
return(0);
}
Output
Final copied string : This is tu
C library function strcpy() example
#include <stdio.h>
#include <stdlib.h>
int main()
{
char str1[10]= "awesome";
char str2[10];
char str3[10];
strcpy(str2, str1);
strcpy(str3, "well");
puts(str2);
puts(str3);
return 0;
}
Output
awesome
well
C library function strcpy() example
#include <stdio.h>
#include <stdlib.h>
int main()
{
char str1[10]= "awesome";
char str2[10];
char str3[10];
strcpy(str2, str1);
strcpy(str3, "well");
puts(str2);
puts(str3);
return 0;
}
Output
awesome
well
C library function strcoll() example
#include <stdio.h>
#include <string.h>
int main () {
char str1[15];
char str2[15];
int ret;
strcpy(str1, "abc");
strcpy(str2, "ABC");
ret = strcoll(str1, str2);
if(ret > 0) {
printf("str1 is less than str2");
} else if(ret < 0) {
printf("str2 is less than str1");
} else {
printf("str1 is equal to str2");
}
return(0);
}
Output
str1 is less than str2
C library function strncmp() example
#include <stdio.h>
#include <string.h>
int main () {
char str1[15];
char str2[15];
int ret;
strcpy(str1, "abcdefg");
strcpy(str2, "ABCDEFG");
ret = strncmp(str1, str2, 4);
if(ret < 0) {
printf("str1 is less than str2");
} else if(ret > 0) {
printf("str2 is less than str1");
} else {
printf("str1 is equal to str2");
}
return(0);
}
Output
str2 is less than str1
C library function strcmp() example
#include <stdio.h>
#include <stdlib.h>
int main()
{
char str1[] = "abcd", str2[] = "abCd", str3[] = "abcd";
int result;
// comparing strings str1 and str2
result = strcmp(str1, str2);
printf("strcmp(str1, str2) = %d\n", result);
// comparing strings str1 and str3
result = strcmp(str1, str3);
printf("strcmp(str1, str3) = %d\n", result);
return 0;
}
Output
strcmp(str1, str2) = 32
strcmp(str1, str3) = 0
C library function strchr() example
#include <stdio.h>
#include <stdlib.h>
int main () {
const char str[] = "http://www.tutorialsroot.com";
const char ch = '.';
char *ret;
ret = strchr(str, ch);
printf("String after |%c| is - |%s|\n", ch, ret);
return(0);
}
Output
String after |.| is - |.tutorialsroot.com|
C library function strncat() example
#include <stdio.h>
#include <stdlib.h>
int main () {
char src[50], dest[50];
strcpy(src, "It is source");
strcpy(dest, "IT is destination");
strncat(dest, src, 15);
printf("Final destination string : |%s|", dest);
return(0);
}
Output
Final destination string : |IT is destinationThis is source|
C library function strcat() example
#include <stdio.h>
#include <stdlib.h>
int main()
{
char str1[] = "This is ", str2[] = "tutorialsroot.com";
//concatenates str1 and str2 and resultant string is stored in str1.
strcat(str1,str2);
puts(str1);
puts(str2);
return 0;
}
Output
This is tutorialsroot.com
tutorialsroot.com
C library function memset() example
#include <stdio.h>
#include <stdlib.h>
int main () {
char str[50];
strcpy(str,"It is string.h library function");
puts(str);
memset(str,'$',7);
puts(str);
return(0);
}
Output
This is string.h library function
$$$$$$$ string.h library function
C library function memmove() example
#include <stdio.h>
#include <stdlib.h>
int main () {
char dest[] = "oldstring";
const char src[] = "newstring";
printf("Before memmove dest = %s, src = %s\n", dest, src);
memmove(dest, src, 9);
printf("After memmove dest = %s, src = %s\n", dest, src);
return(0);
}
Output
Before memmove dest = oldstring, src = newstring
After memmove dest = newstring, src = newstring
C library function memcpy() example
#include <stdio.h>
#include <stdlib.h>
int main () {
const char src[50] = "http://www.tutorialsroot.com";
char dest[50];
strcpy(dest,"Hiiii!!");
printf("Before memcpy dest = %s\n", dest);
memcpy(dest, src, strlen(src)+1);
printf("After memcpy dest = %s\n", dest);
return(0);
}
Output
Before memcpy dest =
After memcpy dest = http://www.tutorialsroot.com
C library function memcmp() example
#include <stdio.h>
#include <stdlib.h>
int main () {
char str1[15];
char str2[15];
int ret;
memcpy(str1, "abcdef", 6);
memcpy(str2, "ABCDEF", 6);
ret = memcmp(str1, str2, 5);
if(ret > 0) {
printf("str2 is less than str1");
} else if(ret < 0) {
printf("str1 is less than str2");
} else {
printf("str1 is equal to str2");
}
return(0);
}
Output
str2 is less than str1
C library function memchr() example
#include <stdio.h>
#include <stdlib.h>
int main () {
const char str[] = "http://www.tutorialsroot.com";
const char ch = '.';
char *ret;
ret = memchr(str, ch, strlen(str));
printf("String after |%c| is - |%s|\n", ch, ret);
return(0);
}
Output
String after |.| is - |.tutorialsroot.com|
C library function wctomb() example
#include <stdio.h>
#include <stdlib.h>
int main () {
int i;
wchar_t wc = L'a';
char *pmbnull = NULL;
char *pmb = (char *)malloc(sizeof( char ));
printf("Converting wide character:\n");
i = wctomb( pmb, wc );
printf("Characters converted: %u\n", i);
printf("Multibyte character: %.1s\n", pmb);
printf("Trying to convert when target is NULL:\n");
i = wctomb( pmbnull, wc );
printf("Characters converted: %u\n", i);
/* this will not print any value */
printf("Multibyte character: %.1s\n", pmbnull);
return(0);
}
Output
Converting wide character:
Characters converted: 1
Multibyte character: a
Trying to convert when target is NULL:
Characters converted: 0
Multibyte character:
C library function mbtowc() example
#include <stdio.h>
#include <stdlib.h>
int main()
{
char pmb[] = "Welcome to Tutorialaaroot.com";
wchar_t pwc[100];
int len, ret_val;
/* resets internal conversion state */
mbtowc (NULL, NULL, 0);
len = strlen(pmb);
ret_val = mbtowc(pwc, pmb, strlen(pmb));
cout << "Return Value = " << ret_val << endl;
wcout << "Wide character string: " << pwc;
return(0);
}
Output
Return Value = 1
Wide character string: W@
C library function mbstowcs() example
#include <stdio.h>
#include <stdlib.h>
using namespace std;
int main()
{
char src[] = "\xc4\xe3\xba\xc3";
wchar_t dest[10];
int num;
num = mbstowcs(dest, src, MB_CUR_MAX);
cout << "Number of wide character converted = " << num << endl;
wcout << "Wide Character String = " << dest << endl;
return 0;
}
Output
Number of wide character converted = 1
Wide Character String = ─
C library function mblen() example
#include <stdio.h>
#include <stdlib.h>
using namespace std;
int main()
{
int len;
char *s = (char *)malloc(20);
strcpy(s,"\xe4\xbd\xa0\xe5\xa5\xbd");
/* resets the conversion state */
mblen(NULL, 0);
len = mblen(s,strlen(s));
cout << "Length of multibyte character: " << len << endl;
return 0;
}
Output
Length of multibyte character: 1
C library function srand() example
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main () {
int i, n;
time_t t;
n = 5;
srand((unsigned) time(&t));
for( i = 0 ; i < n ; i++ ) {
printf("%d\n", rand() % 50);
}
return(0);
}
Output
38
45
29
29
47
C library function rand() example
#include <stdio.h>
#include <stdlib.h>
int main () {
int i, n;
time_t t;
n = 5;
srand((unsigned) time(&t));
for( i = 0 ; i < n ; i++ ) {
printf("%d\n", rand() % 50);
}
return(0);
}
Output
38
45
29
29
47
C library function ldiv() example
#include <stdio.h>
#include <stdlib.h>
int main () {
ldiv_t output;
output = ldiv(100000L, 30000L);
printf("Quotient = %ld\n", output.quot);
printf("Remainder = %ld\n", output.rem);
return(0);
}
Output
Quotient = 3
Remainder = 10000
C library function labs() example
#include <stdio.h>
#include <stdlib.h>
int main()
{
float num, root;
printf("Enter a number: ");
scanf("%f", &num);
// Computes the square root of num and stores in root.
root = sqrt(num);
printf("Square root of %.2f = %.2f", num, root);
return 0;
}
Output
Enter a number: 12
Square root of 12.00 = 3.46