fix some type mismatch issues

cnpy.cpp

@@ -65,7 +65,7 @@ void cnpy::parse_npy_header(unsigned char* buffer,size_t& word_size, std::vector
     uint16_t header_len = *reinterpret_cast<uint16_t*>(buffer+8);
     std::string header(reinterpret_cast<char*>(buffer+9),header_len);
 
-    int loc1, loc2;
+    size_t loc1, loc2;
 
     //fortran order
     loc1 = header.find("fortran_order")+16;
@@ -108,19 +108,19 @@ void cnpy::parse_npy_header(FILE* fp, size_t& word_size, std::vector<size_t>& sh
     std::string header = fgets(buffer,256,fp);
     assert(header[header.size()-1] == '\n');
 
-    int loc1, loc2;
+    size_t loc1, loc2;
 
     //fortran order
     loc1 = header.find("fortran_order");
-    if (loc1 < 0)
+    if (loc1 == std::string::npos)
         throw std::runtime_error("parse_npy_header: failed to find header keyword: 'fortran_order'");
     loc1 += 16;
     fortran_order = (header.substr(loc1,4) == "True" ? true : false);
 
     //shape
     loc1 = header.find("(");
     loc2 = header.find(")");
-    if (loc1 < 0 || loc2 < 0)
+    if (loc1 == std::string::npos || loc2 == std::string::npos)
         throw std::runtime_error("parse_npy_header: failed to find header keyword: '(' or ')'");
 
     std::string str_shape = header.substr(loc1+1,loc2-loc1-1);
@@ -138,7 +138,7 @@ void cnpy::parse_npy_header(FILE* fp, size_t& word_size, std::vector<size_t>& sh
     //byte order code | stands for not applicable. 
     //not sure when this applies except for byte array
     loc1 = header.find("descr");
-    if (loc1 < 0)
+    if (loc1 == std::string::npos)
         throw std::runtime_error("parse_npy_header: failed to find header keyword: 'descr'");
     loc1 += 9;
     bool littleEndian = (header[loc1] == '<' || header[loc1] == '|' ? true : false);
@@ -313,7 +313,7 @@ cnpy::NpyArray cnpy::npz_load(std::string fname, std::string varname) {
         }
         else {
             //skip past the data
-            size_t size = *(uint32_t*) &local_header[22];
+            uint32_t size = *(uint32_t*) &local_header[22];
             fseek(fp,size,SEEK_CUR);
         }
     }