/* * File: strlib.c * Last modified on Fri Jul 15 14:10:41 1994 by eroberts * ----------------------------------------------------- * This file implements the strlib interface. *//* * General implementation notes: * ----------------------------- * This module implements the strlib library by mapping all * functions into the appropriate calls to the ANSI <string.h> * interface.  The implementations of the individual functions * are all quite simple and do not require individual comments. * For descriptions of the behavior of each function, see the * interface. */#include <stdio.h>#include <string.h>#include <ctype.h>#include "genlib.h"#include "strlib.h"/* * Constant: MaxDigits * ------------------- * This constant must be larger than the maximum * number of digits that can appear in a number. */#define MaxDigits 30/* Private function prototypes */static string CreateString(int len);/* Section 1 -- Basic string operations */string Concat(string s1, string s2){    string s;    int len1, len2;    if (s1 == NULL || s2 == NULL) {        Error("NULL string passed to Concat");    }    len1 = strlen(s1);    len2 = strlen(s2);    s = CreateString(len1 + len2);    strcpy(s, s1);    strcpy(s + len1, s2);    return (s);}char IthChar(string s, int i){    int len;    if (s == NULL) Error("NULL string passed to IthChar");    len = strlen(s);    if (i < 0 || i > len) {        Error("Index outside of string range in IthChar");    }    return (s[i]);}string SubString(string s, int p1, int p2){    int len;    string result;    if (s == NULL) Error("NULL string passed to SubString");    len = strlen(s);    if (p1 < 0) p1 = 0;    if (p2 >= len) p2 = len - 1;    len = p2 - p1 + 1;    if (len < 0) len = 0;    result = CreateString(len);    strncpy(result, s + p1, len);    result[len] = '\0';    return (result);}string CharToString(char ch){    string result;    result = CreateString(1);    result[0] = ch;    result[1] = '\0';    return (result);}int StringLength(string s){    if (s == NULL) Error("NULL string passed to StringLength");    return (strlen(s));}string CopyString(string s){    string newstr;    if (s == NULL) Error("NULL string passed to CopyString");    newstr = CreateString(strlen(s));    strcpy(newstr, s);    return (newstr);}/* Section 2 -- String comparison functions */bool StringEqual(string s1, string s2){    if (s1 == NULL || s2 == NULL) {        Error("NULL string passed to StringEqual");    }    return (strcmp(s1, s2) == 0);}int StringCompare(string s1, string s2){    if (s1 == NULL || s2 == NULL) {        Error("NULL string passed to StringCompare");    }    return (strcmp(s1, s2));}/* Section 3 -- Search functions */int FindChar(char ch, string text, int start){    char *cptr;    if (text == NULL) Error("NULL string passed to FindChar");    if (start < 0) start = 0;    if (start > strlen(text)) return (-1);    cptr = strchr(text + start, ch);    if (cptr == NULL) return (-1);    return ((int) (cptr - text));}int FindString(string str, string text, int start){    char *cptr;    if (str == NULL) Error("NULL pattern string in FindString");    if (text == NULL) Error("NULL text string in FindString");    if (start < 0) start = 0;    if (start > strlen(text)) return (-1);    cptr = strstr(text + start, str);    if (cptr == NULL) return (-1);    return ((int) (cptr - text));}/* Section 4 -- Case-conversion functions */string ConvertToLowerCase(string s){    string result;    int i;    if (s == NULL) {        Error("NULL string passed to ConvertToLowerCase");    }    result = CreateString(strlen(s));    for (i = 0; s[i] != '\0'; i++) result[i] = tolower(s[i]);    result[i] = '\0';    return (result);}string ConvertToUpperCase(string s){    string result;    int i;    if (s == NULL) {        Error("NULL string passed to ConvertToUpperCase");    }    result = CreateString(strlen(s));    for (i = 0; s[i] != '\0'; i++) result[i] = toupper(s[i]);    result[i] = '\0';    return (result);}/* Section 5 -- Functions for converting numbers to strings */string IntegerToString(int n){    char buffer[MaxDigits];    sprintf(buffer, "%d", n);    return (CopyString(buffer));}int StringToInteger(string s){    int result;    char dummy;    if (s == NULL) {        Error("NULL string passed to StringToInteger");    }    if (sscanf(s, " %d %c", &result, &dummy) != 1) {        Error("StringToInteger called on illegal number %s", s);    }    return (result);}string RealToString(double d){    char buffer[MaxDigits];    sprintf(buffer, "%G", d);    return (CopyString(buffer));}double StringToReal(string s){    double result;    char dummy;    if (s == NULL) Error("NULL string passed to StringToReal");    if (sscanf(s, " %lg %c", &result, &dummy) != 1) {        Error("StringToReal called on illegal number %s", s);    }    return (result);}/* Private functions *//* * Function: CreateString * Usage: s = CreateString(len); * ----------------------------- * This function dynamically allocates space for a string of * len characters, leaving room for the null character at the * end. */static string CreateString(int len){    return ((string) GetBlock(len + 1));}