I'm trying to implement strcat() in C but stuck on that the output result is repeated src.
here is my code.
void my_strcat(char des[], char src[]) {
int i = 0, j = 0;
while (des[i] != '\0')
i += 1;
while (src[j] != '\0') {
des[i + j] = src[j];
j += 1;
}
des[i + j] = '\0';
printf("%s", des);
}
int main() {
char des[1000], src[100];
for(int i = 0; i < 2; ++i) {
printf("src: ");
scanf("%s", src);
my_strcat(des, src);
}
printf("%s", des);
}
the output is not the same as I was expected before. It's like for example:
src: a
src: b
des: aabb
You probably want this:
#include <stdio.h>
#include <stdlib.h>
void my_strcat(char des[], const char src[]) { // better use const her
int i = 0, j = 0;
while (des[i] != '\0')
i += 1;
while (src[j] != '\0') {
des[i + j] = src[j];
j += 1;
}
des[i + j] = '\0';
// printf("%s", des); // dont print des here
}
int main() {
char des[1000];
char src[100];
des[0] = 0; // initialize des to a zero length string
for (int i = 0; i < 2; ++i) {
printf("src: ");
scanf("%s", src);
my_strcat(des, src);
}
printf("%s", des); // print the destination
}
Related
I have to split an initial char and create a list of said char which has to end with a NULL so i can iterate over in the main without knowing list size. The problem is that i get a seg fault whenever i try to check if last element is NULL. i am sorry i am still trying to learn both C and english. Thank you all
#include <stdlib.h>
#include <stdio.h>
char **split(const char *s) {
char **split;
unsigned m_size = 0, c_size, i, j, k;
// get s size
for (i = 0; s[i] != '\0'; i++) {
if (s[i] == ' ') {
m_size++;
}
}
m_size++;
split = (char**) malloc(sizeof(char) * (m_size + 1));
int sizes[m_size];
c_size = 0;
// get s words size
for (i = 0, j = 0; s[i] != '\0'; i++) {
if (s[i] == ' ') {
c_size++;
sizes[j] = c_size;
c_size = 0;
j++;
} else {
c_size++;
}
}
sizes[j] = c_size;
for (i = 0; i < m_size; i++) {
split[i] = (char *) malloc(sizeof(char) * sizes[i]);
}
split[i] = NULL;
for (i = 0, j = 0, k = 0; s[i] != '\0'; i++) {
if (s[i] != ' ') {
split[j][k] = s[i];
k++;
} else {
split[j][k] = '\0';
j++;
k = 0;
}
}
return split;
}
int main() {
char s[19] = "hello how are you?";
char **splitted;
unsigned i;
splitted = split(s);
if (splitted == NULL) {
return 1;
}
for (i = 0; splitted[i]!=NULL; i++) {
printf("%s\n", splitted[i]);
}
return 0;
}
EDIT
#include <stdlib.h>
#include <stdio.h>
char **split(const char *s) {
char **r;
unsigned word_size = 0;
unsigned list_size = 0, i, j, k;
// get s size
for (i = 0; s[i] != '\0'; i++) {
if (s[i] != ' ') {
word_size++;
} else {
if (word_size > 0) {
list_size++;
word_size = 0;
}
}
}
list_size++;
r = malloc(sizeof(*r) * (list_size + 1));
int char_sizes[list_size];
for (i = 0; i < list_size; char_sizes[i] = 0, i++);
// get s words size
for (i = 0, j = 0; s[i] != '\0'; i++) {
if (s[i] != ' ') {
char_sizes[j]++;
} else {
if (char_sizes[j] > 0) {
j++;
}
}
}
for (i = 0; i < list_size; i++) {
r[i] = malloc(sizeof(char) * char_sizes[i]);
}
r[i] = NULL;
for (i = 0, j = 0, k = 0; s[i] != '\0'; i++) {
if (s[i] != ' ') {
r[j][k] = s[i];
k++;
} else {
if (k > 0) {
r[j][k] = '\0';
j++;
k = 0;
}
}
}
return r;
}
void destroy(char **list) {
unsigned i;
for (i = 0; list[i] != NULL; i++) {
free(list[i]);
}
free(list);
}
int main() {
char s[100] = " hello guys how are? you,d 31 3 ";
char **splitted;
unsigned i;
splitted = split(s);
if (splitted == NULL) {
return 1;
}
for (i = 0; splitted[i]!=NULL; i++) {
printf("%s", splitted[i]);
}
destroy(splitted);
return 0;
}
ok guys i followed your tips and i edited my code. leaving this here if someone wants to point out other errors i will appreciate. now it should work even with multiple spaces. thanks to all
Your are requesting an "array" of pointers to char, but you are allocating an "array" of chars:
split = (char**) malloc(sizeof(char) * (m_size + 1));
should become
split = malloc(sizeof(char*) * (m_size + 1));
Note the sizeof(char*). BTW: Note that in C, you should not cast the result of malloc as explained in this SO post.
I hope you can help me I worked on this code. The code works like this
user inputs a string for example "hey john, how are you john?
the program erases signs like "'?' , ',' '!' " etc.
the program writes a string after erasing the signs : "hey john how are you john?"
and the code outputs the frequency of each word:
hey : 1
john: 2
how : 1
are : 1
you : 1
but my code counts sometimes wrong. For example when I type "bye bye bye hello hello hello"
the output is :
bye : 3
hello : 1
My code does the john example right, but the bye bye... example wrong.
How do I have to change my code? Thank you
#include <stdio.h>
#include <string.h>
char words[80][80];
void clear_string(char *text);
int extract_and_count(char *source, int *count);
void clearArray(char array[]);
int indexInWords(char string[]);
void print(int countOfWords, int count[]);
int equals(char *string1, char *string2);
int main() {
char string[80];
int count[80];
printf("please enter your text: ");
scanf("%[^\n]s", string);
clear_string(string);
printf("%s\n", string);
int countOfWords = extract_and_count(string, count);
print(countOfWords, count);
return 0;
}
void clear_string(char *text){
int i = 0;
for(;i < strlen(text);++i){
if( text[i] == '.' || text[i] == ',' || text[i] == '!' || text[i] == '?'){
int k = i + 1;
for(; k < strlen(text);++k){
text[k-1] = text[k];
}
k = strlen(text) - 1;
text[k] = ' ';
}
}
}
int extract_and_count(char *source, int *count){
int wordCounter = 0;
char string[80];
int i = 0, k = 0;
clearArray(string);
for(; i < strlen(source);++i, ++k){
if(source[i] != ' '){
string[k] = source[i];
}else{
if(string[0] == '\0'){
break;
}
int index = indexInWords(string);
if(index == -1){
strcpy(words[wordCounter], string);
count[wordCounter] = 1;
wordCounter++;
}else{
count[index] += 1;
}
clearArray(string);
k = -1;
}
}
return wordCounter;
}
void clearArray(char array[]){
memset(array,0,strlen(array));
//array[0] = '\0';
}
int indexInWords(char string[]){
int i = 0;
for(;i < 80;++i){
if(equals(words[i], string) == 0){
return i;
}
}
return -1;
}
void print(int countOfWords, int count[]){
for(int i = 0;i < countOfWords; ++i){
printf("%s : %d\n",words[i], count[i]);
}
}
int equals(char string1[], char string2[]){
return strcmp(string1, string2);
}
The most significant problem I found was in extract_and_count() -- it doesn't count the last word as it only counts words followed by space. The bandaid is to check if string has anything in it after the loop, and if so, process it. Below is my rework for that fix and general style:
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
void clear_string(char *text);
int extract_and_count(char *source, int count[]);
void clearArray(char array[]);
int indexInWords(char string[]);
void print(int countOfWords, int count[]);
bool equals(char *string1, char *string2);
#define BUFFER_SIZE (512)
#define MAX_WORD_COUNT (80)
#define MAX_WORD_SIZE (64)
char words[MAX_WORD_COUNT][MAX_WORD_SIZE];
int main() {
char string[BUFFER_SIZE];
int count[MAX_WORD_COUNT];
printf("Please enter your text: ");
while (fgets(string, BUFFER_SIZE, stdin) == NULL) {
printf("Please (re)enter your text: ");
}
clear_string(string);
int countOfWords = extract_and_count(string, count);
print(countOfWords, count);
return 0;
}
void clear_string(char *text) {
for (int i = 0; i < strlen(text); i++) {
if (text[i] == '.' || text[i] == ',' || text[i] == '!' || text[i] == '?' || text[i] == '\n') {
int length = strlen(text);
for (int k = i + 1; k < length; k++) {
text[k - 1] = text[k];
}
text[length - 1] = '\0';
i--;
}
}
}
int extract_and_count(char *source, int count[]) {
int wordCounter = 0;
char string[MAX_WORD_SIZE] = {'\0'};
for (int i = 0, k = 0; i < strlen(source); i++, k++) {
if (source[i] != ' ') {
string[k] = source[i];
} else {
if (string[0] == '\0') {
break;
}
int index = indexInWords(string);
if (index == -1) {
strcpy(words[wordCounter], string);
count[wordCounter] = 1;
wordCounter++;
} else {
count[index] += 1;
}
clearArray(string);
k = -1;
}
}
if (string[0] != '\0') {
int index = indexInWords(string);
if (index == -1) {
strcpy(words[wordCounter], string);
count[wordCounter] = 1;
wordCounter++;
} else {
count[index] += 1;
}
}
return wordCounter;
}
void clearArray(char array[]) {
memset(array, 0, strlen(array));
}
int indexInWords(char string[]) {
for (int i = 0; i < MAX_WORD_COUNT; i++) {
if (equals(words[i], string)) {
return i;
}
}
return -1;
}
void print(int countOfWords, int count[]) {
for (int i = 0; i < countOfWords; i++) {
printf("%s : %d\n", words[i], count[i]);
}
}
bool equals(char string1[], char string2[]) {
return strcmp(string1, string2) == 0;
}
The next most significant issue I see is you don't keep track of how many entries in words[][] are used, so indexInWords() could easily wander off making comparisons against uninitialized memory.
In extract_and_count you break out of the for-loop when you find 2 spaces. Also you did not check for the last word of source. Changed it to:
int extract_and_count(char *source, int *count){
int wordCounter = 0;
char string[80];
int i = 0, k = 0;
clearArray(string);
for(; i < strlen(source)+1;++i, ++k){
if(source[i] != ' ' && source[i] != 0){
string[k] = source[i];
}else{
if(string[0] != '\0'){
int index = indexInWords(string);
if(index == -1){
strcpy(words[wordCounter], string);
count[wordCounter] = 1;
wordCounter++;
}else{
count[index] += 1;
} }
clearArray(string);
k = -1;
}
}
return wordCounter;
}
my program works fine if i give hard code value to char *w="ls -l" but i am trying to take input form user not working help my code:: using input error occur
i don't understand the concept of fgets using fgets its gives the garbig value to execv
#include<stdio.h>
#include<sys/wait.h>
#include<stdbool.h>
void func(char **arr, char *w)
{
int i = 0, j = 0, k = 0;
char temp[100];
for (i = 0; i < 100; i++)
{
if (w[i] == '')
{
arr[k] = temp;
arr[k+1] = NULL;
break;
}
if (w[i] == ' ')
{
arr[k] = temp;
k++;
j = 0;
}
else
{
temp[j] = w[i];
j++;
}
}
}
int main()
{
char *n = "/bin/ls";
char *arr[10] = {''};
char p[100] = {''};
char *w = "ls -l";
int i = 0;
//printf("bilal-hassan-qadri $ >>");
//fgets(p, 100, stdin);
arr[2] = NULL;
bool found = false;
for (i = 0; i < sizeof(w); i++)
{
if (w[i] == ' ')
{
found=true;
func(arr,w);
break;
}
}
if (!found)
arr[0] = w;
int status;
int id = fork();
if (id == 0)
{
if (execv(n,arr) < 0)
{
printf("invalid commandn");
}
else
{
printf("ninvalid command");
}
}
else
{
wait(&status);
}
}
In the function func, You have to copy the string to elements of arr
instead of just passing the address of temp, which will vanish on leaving the function.
You can use strdup instead of copy_string if your system supports it.
You have to terminate the string in temp before copying it.
Empty string constant '' seems invalid. You shouldn't use it.
fgets stores new-line character \n if it exists. Check for it and remove if it isn't wanted.
Fixed code:
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<sys/wait.h>
#include<stdbool.h>
char *copy_string(const char *str) {
char *s = malloc(strlen(str) + 1);
if (s) strcpy(s, str); else {perror("malloc"); exit(1);}
return s;
}
void func(char **arr, char *w)
{
int i = 0, j = 0, k = 0;
char temp[100];
for (i = 0; i < 100; i++)
{
if (w[i] == '\0' || w[i] == '\n')
{
temp[j] = '\0';
arr[k] = copy_string(temp);
arr[k+1] = NULL;
break;
}
if (w[i] == ' ')
{
temp[j] = '\0';
arr[k] = copy_string(temp);
k++;
j = 0;
}
else
{
temp[j] = w[i];
j++;
}
}
}
int main(void)
{
char *n = "/bin/ls";
char *arr[10] = {NULL};
char p[100] = {0};
char *w = "ls -l";
int i = 0;
//printf("bilal-hassan-qadri $ >>");
fgets(p, 100, stdin);
w = p;
arr[2] = NULL;
bool found = false;
for (i = 0; w[i] != '\0'; i++)
{
if (w[i] == ' ')
{
found=true;
func(arr,w);
break;
}
}
if (!found)
arr[0] = w;
int status;
int id = fork();
if (id == 0)
{
if (execv(n,arr) < 0)
{
printf("invalid commandn");
}
else
{
printf("ninvalid command");
}
}
else
{
wait(&status);
for (i = 0; arr[i] != NULL; i++) free(arr[i]);
}
return 0;
}
Program i've wrote is calculating how many times each letter appears in a string. I want to change it that it will find the character that appears the great amount of times in a row i.e. for the string "aabbbcccca" i want to printf "c" (as there are four c in a row and only two a and three b).
How to change my program that it will do the things i want? I am looking for the solution that will be as simple as possible and I want to use the existing code as much as possible.
#include "stdafx.h"
#include "string.h"
#include "ctype.h"
int count_nonspace(const char* str)
{
int count = 0;
while (*str)
{
if (!isspace(*str++))
count++;
}
return count;
}
int _tmain(int argc, _TCHAR* argv[])
{
int a[127];
int i = 0, j = 0, count[127] = { 0 };
char string[100] = "Hello world";
for (i = 0; i < strlen(string); i++)
{
for (j = 33; j<127; j++)
{
if (string[i] == (j))
{
count[j]++;
}
}
}
for (j = 0; j< 127; j++)
{
if (count[j] > 0)
if (j < ' ' + 1)
printf("\n%d -> %d", count[j], j);
else
printf("\n%d -> %c", count[j], char(j));
}
}
My idea for changing the code is the following (posted only the changed part):
but still results are not as anticipated, why is that?
for (i = 0; i < strlen(string); i++)
{
for (j = 33; j<127; j++)
{
if (string[i] == (j))
{
count[j]++;
if (string[i] == string[i + 1])
count[j]++;
else
best[j] = count[j];
}
}
}
#include "stdafx.h"
#include "string.h"
#include "ctype.h"
int count_nonspace(const char* str)
{
int count = 0;
while (*str)
{
if (!isspace(*str++))
count++;
}
return count;
}
int _tmain(int argc, _TCHAR* argv[])
{
int a[127];
int i = 0, j = 0, count[127] = { 0 };
int cur_count = 1; /* Gets compared with value in count[] */
char cur_char = '\0';
char string[100] = "Hello world";
for (i = 0; i < strlen(string); i++)
{
if(cur_char == string[i])
{
cur_count++;
}
else
{
if(32 < cur_char && cur_char < 127)
{
if(cur_count > count[cur_char])
{
count[cur_char] = cur_count;
}
}
cur_char = string[i];
cur_count = 1;
if(32 < cur_char && cur_char < 127)
{
if(!(count[cur_char]))
{
count[cur_char] = cur_count;
}
}
}
}
/* Find the most consecutive char and print it. */
char max_char = '\0';
int max_count = 0;
for(j = 0; j < 127; j++)
{
if(max_count < count[j])
{
max_count = count[j];
max_char = j;
}
}
printf("%c\n", max_char);
}
I have a garbage problem in my array in C, that I can't solve and I have used the memset function for this but this is not useful to me. how can I solve this problem. If I run this code in Code Block or other PC then this is not run completely.
Here is my code:
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <string.h>
int main() {
clrscr();
int a, b, len = 0, x, i = 0, j, match, misMatch, gapPenalty, sim, m1, m2, m3;
char ch;
char *seq1 = (char *)malloc(100 * sizeof(char));
char *seq2 = (char *)malloc(100 * sizeof(char));
char *s1 = (char *)malloc(100 * sizeof(char));
char *s2 = (char *)malloc(100 * sizeof(char));
/*memset(seq1, 0, strlen(seq1) - 1);
memset(seq2, 0, strlen(seq2) - 1);
memset(s1, 0, strlen(s1) - 1);
memset(s2, 0, strlen(s2) - 1);*/
int **matrix;
int **back;
FILE *inputFile;
inputFile = fopen("in.txt", "r");
printf("Enter Match Point : ");
scanf("%d", &match);
printf("Enter Mismatch Point : ");
scanf("%d", &misMatch);
printf("Enter Gap Point : ");
scanf("%d", &gapPenalty);
while (fscanf(inputFile,"%s\n%s", seq1, seq2) != EOF);
a = strlen(seq1);
b = strlen(seq2);
for (j = 0; j <= strlen(seq2); j++) {
for (i = 0; i <= strlen(seq1); i++) {
if (i == 0 || j == 0) {
if (i == 0) {
matrix[j][i] = j * gapPenalty;
back[j][i] = 0;
}
if (j == 0) {
matrix[j][i] = i * gapPenalty;
back[j][i] = 0;
}
} else {
if (seq1[i - 1] == seq2[j - 1]) {
sim = match;
} else {
sim = misMatch;
}
m1 = matrix[j - 1][i - 1] + sim;
m2 = matrix[j - 1][i] + gapPenalty;
m3 = matrix[j][i - 1] + gapPenalty;
if (m1 > m2) {
if (m1 > m3) {
matrix[j][i] = m1;
back[j][i] = 1;
} else {
matrix[j][i] = m3;
back[j][i] = 3;
}
} else {
if (m2 > m3) {
matrix[j][i] = m2;
back[j][i] = 2;
} else {
matrix[j][i] = m3;
back[j][i] = 3;
}
}
}
}
}
printf("%s", seq1);
printf("\n");
printf("%s", seq2);
printf("\n");
if (a > b) {
len = a;
} else {
len = b;
}
for (x = 0; x < len; x++) {
if (back[b][a] == 1) {
s1[x] = seq1[a - 1];
s2[x] = seq2[b - 1];
a = a - 1;
b = b - 1;
} else if(back[b][a] == 2) {
s1[x] = seq1[a - 1];
s2[x] = '-';
a = a - 1;
} else {
s1[x] = '-';
s2[x] = seq2[b - 1];
b = b - 1;
}
}
for (j = 0; j <= strlen(seq2); j++) {
for (i = 0; i <= strlen(seq1); i++) {
printf("%d ", matrix[j][i]);
}
printf("\n");
}
printf("\n");
for (j = 0; j <= strlen(seq2); j++) {
for (i = 0; i <= strlen(seq1); i++) {
printf("%d ", back[j][i]);
}
printf("\n");
}
printf("\n");
printf("%s", s1);
printf("\n");
printf("%s", s2);
printf("\n");
free(s1);
free(s2);
free(matrix);
free(back);
getch();
return 0;
}
Use calloc(). calloc() initializes all the allocated memory to 0.
// sizeof (char), by definition, is 1
char *seq1 = calloc(100, 1);
char *seq2 = calloc(100, 1);
char *s1 = calloc(100, 1);
char *s2 = calloc(100, 1);
The immediate problem with your commented code is that you cannot apply strlen() to an uninitialized array. You should be using the correct size (which you just used a few statements before) instead
/*memset(seq1, 0, 100);
memset(seq2, 0, 100);
memset(s1, 0, 100);
memset(s2, 0, 100);*/