strcat

问题 I'm having a problem with the program below. I'm trying to scan through a string command entered by the user for certain words. My major issue right now is that when I run the following I get a warning saying that "passing arg 2 of `strcat' makes pointer from integer without a cast". My intent is to loop through the first three characters of the string "s", concatenate them onto a string "firstthree", and later check the value of the string "firstthree". Any help is appreciated. #include

问题 This question already has answers here : How do I concatenate const/literal strings in C? (17 answers) Closed last year . I know I shouldn't be using that function, and I don't care. Last time I checked the spec for strcat, it said something along the lines of updating the first value as well as returning the same. Now, this is a really stupid question, and I want you to explain it like you're talking to a really stupid person. Why won't this work? char* foo="foo"; printf(strcat(foo,"bar"));

问题 My implementation of strcat(char*, const char*) seems to work but then it causes a core dump. strcat() implementation: char* strcat(char* dest, const char* src) { char* tmp = dest; while(*tmp) ++tmp ; while( (*tmp++ = *src++ ) != '\0') ; return (dest); } Code in int main() where I call strcat(): char arr3[] = "Mr. "; char arr4[] = "Smith"; printf("Hello %s!", strcat(arr3, arr4)); It actually concatenated both strings and printed it out but still caused a core dump. output : Hello Mr. Smith

问题 I am trying to concatenate 2 character arrays but when I try it does not work and my o/p console hangs and does not print anything. char *str[2]; str[0] = "Hello "; str[1] = "World"; strcat(str[0],str[1]); printf("%s\n",str[0]); I even tried the below code which fails as well char *str1 = "Hello "; char *str2 = "World"; strcat(str1,str2); printf("%s\n",str1); Can someone explain this? TIA. 回答1: char *str1 = "Hello "; char *str2 = "World"; strcat(str1,str2); printf("%s\n",str1); Here you have

问题 char r[40]; strcpy(r,"abcdef"); strcat(r,r); My program crashes at the third line? Replacing strcat(r,r); by strcat(r,"abcdef"); works fine though.... why is that? 回答1: strcat() reads from the input and copies it to the output until it find a \0 terminator in the input. By specifying the same array for both input and output, you are modifying the input while it is being read from. You would have to check your compiler's particular implementation of strcat() , but if you trace through a simple

问题 For some reason after coming back from years of not programming in C I cannot make this work: (This compiles with no complain but it's causing a crash, when I remove the strcat line the executable runs fine) #include <stdio.h> #include <string.h> int main(int argc, char **argv){ char clibdir[50] = "C:\\Users\\______000\\Desktop\\nodeC\\libraries\\c"; char varsfile[20] = "\\variables.xml"; printf("%s\n", clibdir); //ok printf("%s\n", varsfile); //ok char *varspath = strcat(clibdir, varsfile);

问题 I am trying to read a file and then read each character until i reach a new line the do some work on that line. Here is what i have done so far: char line[] = ""; char *charcter = ""; //If i do this here it works fine, but below it's not working at all charcter = "asssss"; strcat(line,charcter); //Read file inputFile = fopen(fileName,"r"); if (inputFile) { while ((charcter = (char)getc(inputFile)) != EOF) strcat(line,charcter); //This piece code keeps crashing my program on run fclose

问题 I have been asked to build the strcat from string.h without using the library and pointers. I have this so far but somehow it doesn't work: void strcatO(char a[], char b[]) { int i = 0; for(i = 0; i < strlen(b); ++i) { a[strlen(a) + i + 1] = b[i]; } printf("%s", a); } Output: 回答1: somehow it doesn't work a[strlen(a) + i + 1] = b[i]; appends characters after a 's null character . void strcatO(char a[], char b[]) { int i = 0; for(i = 0; i < strlen(b); ++i) { a[strlen(a) + i + 1] = b[i]; // Oops

问题 In this code snippet here: printf("shell> "); fgets(input, MAX_INPUT_SIZE, stdin); //tokenize input string, put each token into an array char *space; space = strtok(input, " "); tokens[0] = space; int i = 1; while (space != NULL) { space = strtok(NULL, " "); tokens[i] = space; ++i; } //copy tokens after first one into string strcpy((char*)cmdargs, ("%s ",tokens[1])); for (i = 2; tokens[i] != NULL; i++) { strcat((char*)cmdargs, ("%s ", tokens[i])); } printf((char*)cmdargs); With the input: