Pointers and cstring beginner troubles - c

Question

I have a problem with the function replace. What I want to accomplish is to replace some special characters, but I haven't written the code yet. So in the replace function we can at this moment just say that the function should print line for line the way I have tried to write. Can someone please correct this function? I can’t really get it
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
struct list_el {
char *ord;
int num;
struct list_el *prev;
struct list_el *next;
};
typedef struct list_el item;
struct list_el *head, *tail; /*Double linked list that makes it easier to add a element to the end of the FIFO list*/
void addNode(struct list_el *curr);
void readFile();
void print();
void replace();
void random();
void len();
int antE = 0;
int randint(int max)
{
int a = (max*rand()/(RAND_MAX+1.0));
return a;
}
int main(int argc, char *argv[]) {
item *curr;
struct list_el *pa;
if(argc == 3) {
readFile();
}
if(argc == 1) {
printf("Too few arguments, must bee 3");
} else if(strcmp(argv[1], "print") == 0) {
print();
} else if(strcmp(argv[1], "random") == 0) {
random();
} else if(strcmp(argv[1], "replace") == 0) {
replace();
} else if(strcmp(argv[1], "remove") == 0) {
printf("Random kommando kalt");
} else if(strcmp(argv[1], "len") == 0) {
len();
} else {
printf("Not a valid command");
}
if(argc == 3) {
free(curr);
}
}
void addNode(struct list_el *curr) {
if(head == NULL) {
head = curr;
curr->prev = NULL;
} else {
tail->next = curr;
curr->prev = tail;
}
tail = curr;
curr->next = NULL;
}
void readFile()
{
FILE *f = fopen("tresmaa.txt", "r");
if(f == 0) {
printf("Could not open file");
exit(8);
}
item *curr;
if(f != NULL) {
int antE = 0;
head = NULL;
char buffer[300];
while(fgets(buffer, 300-1,f) != NULL) {
curr = (item*)malloc(sizeof(item));
curr->ord = malloc(300);
curr->num = antE;
strcpy(curr->ord, buffer);
antE++;
addNode(curr);
}
}
fclose(f);
}
/*Traverserer listen og printer ut linje for lije
*/
void print()
{
item *curr;
printf("Print text:\n");
for(curr = head; curr != NULL; curr = curr->next) {
printf("%s", curr->ord);
}
}
/*Printer ut en tilfeldig setning
*/
void random()
{
item *curr;
int anum = randint(antE);
for(curr = head; curr != NULL; curr = curr->next) {
if(curr->num == anum) {
printf("Print a random line:\n%s", curr->ord);
}
}
}
void replace()
{
item *curr;
int i;
char tmp[300];
printf("Replace vowels ...\n");
printf("... with vowel 'a'\n");
for(curr = head; curr != NULL; curr = curr->next) {
strcpy(tmp, curr->ord);
for(i = 0; i < strlen(tmp); i++) {
printf("%s", tmp[i]);
}
}
}
void len()
{
item *curr;
long nc;
int i;
nc = 0;
for(curr = head; curr != NULL; curr = curr->next) {
nc += strlen(curr->ord);
}
printf("The text is %d characters long", nc);
}

Answer 1

If you just want to print the lines you can do it without the copying and extra loop:
for(curr = head; curr != NULL; curr = curr->next) {
printf("%s\n", curr->ord);
}
Your current code doesn't work because you tell printf with the %s format that its argument will be a string (aka. a pointer to a zero-terminated sequence of characters), but then you give it a single character, not such a pointer.